* Execution Model Inversion

This PR inverts the execution model -- from recursively calling nodes to
using a topological sort of the nodes. This change allows for
modification of the node graph during execution. This allows for two
major advantages:

    1. The implementation of lazy evaluation in nodes. For example, if a
    "Mix Images" node has a mix factor of exactly 0.0, the second image
    input doesn't even need to be evaluated (and visa-versa if the mix
    factor is 1.0).

    2. Dynamic expansion of nodes. This allows for the creation of dynamic
    "node groups". Specifically, custom nodes can return subgraphs that
    replace the original node in the graph. This is an incredibly
    powerful concept. Using this functionality, it was easy to
    implement:
        a. Components (a.k.a. node groups)
        b. Flow control (i.e. while loops) via tail recursion
        c. All-in-one nodes that replicate the WebUI functionality
        d. and more
    All of those were able to be implemented entirely via custom nodes,
    so those features are *not* a part of this PR. (There are some
    front-end changes that should occur before that functionality is
    made widely available, particularly around variant sockets.)

The custom nodes associated with this PR can be found at:
https://github.com/BadCafeCode/execution-inversion-demo-comfyui

Note that some of them require that variant socket types ("*") be
enabled.

* Allow `input_info` to be of type `None`

* Handle errors (like OOM) more gracefully

* Add a command-line argument to enable variants

This allows the use of nodes that have sockets of type '*' without
applying a patch to the code.

* Fix an overly aggressive assertion.

This could happen when attempting to evaluate `IS_CHANGED` for a node
during the creation of the cache (in order to create the cache key).

* Fix Pyright warnings

* Add execution model unit tests

* Fix issue with unused literals

Behavior should now match the master branch with regard to undeclared
inputs. Undeclared inputs that are socket connections will be used while
undeclared inputs that are literals will be ignored.

* Make custom VALIDATE_INPUTS skip normal validation

Additionally, if `VALIDATE_INPUTS` takes an argument named `input_types`,
that variable will be a dictionary of the socket type of all incoming
connections. If that argument exists, normal socket type validation will
not occur. This removes the last hurdle for enabling variant types
entirely from custom nodes, so I've removed that command-line option.

I've added appropriate unit tests for these changes.

* Fix example in unit test

This wouldn't have caused any issues in the unit test, but it would have
bugged the UI if someone copy+pasted it into their own node pack.

* Use fstrings instead of '%' formatting syntax

* Use custom exception types.

* Display an error for dependency cycles

Previously, dependency cycles that were created during node expansion
would cause the application to quit (due to an uncaught exception). Now,
we'll throw a proper error to the UI. We also make an attempt to 'blame'
the most relevant node in the UI.

* Add docs on when ExecutionBlocker should be used

* Remove unused functionality

* Rename ExecutionResult.SLEEPING to PENDING

* Remove superfluous function parameter

* Pass None for uneval inputs instead of default

This applies to `VALIDATE_INPUTS`, `check_lazy_status`, and lazy values
in evaluation functions.

* Add a test for mixed node expansion

This test ensures that a node that returns a combination of expanded
subgraphs and literal values functions correctly.

* Raise exception for bad get_node calls.

* Minor refactor of IsChangedCache.get

* Refactor `map_node_over_list` function

* Fix ui output for duplicated nodes

* Add documentation on `check_lazy_status`

* Add file for execution model unit tests

* Clean up Javascript code as per review

* Improve documentation

Converted some comments to docstrings as per review

* Add a new unit test for mixed lazy results

This test validates that when an output list is fed to a lazy node, the
node will properly evaluate previous nodes that are needed by any inputs
to the lazy node.

No code in the execution model has been changed. The test already
passes.

* Allow kwargs in VALIDATE_INPUTS functions

When kwargs are used, validation is skipped for all inputs as if they
had been mentioned explicitly.

* List cached nodes in `execution_cached` message

This was previously just bugged in this PR.

* Add support for simple tooltips

* Fix overflow

* Add tooltips for nodes in the default workflow

* new line

* Prevent potential crash

* PR feedback

* Hide tooltip when clicking (e.g. combo widget)

* Refactor tooltips, add node level support

* Fix

* move

* Fix test (and undo last change)

* Fixed indent

* Fix dom widgets, dont show tooltip if not over canvas

* Add model downloading endpoint.

* Move client session init to async function.

* Break up large function.

* Send "download_progress" as websocket event.

* Fixed

* Fixed.

* Use async mock.

* Move server set up to right before run call.

* Validate that model subdirectory cannot contain relative paths.

* Add download_model test checking for invalid paths.

* Remove DS_Store.

* Consolidate DownloadStatus and DownloadModelResult

* Add progress_interval as an optional parameter.

* Use tuple type from annotations.

* Use pydantic.

* Update comment.

* Revert "Use pydantic."

This reverts commit 7461e8eb.

* Add new line.

* Add newline EOF.

* Validate model filename as well.

* Add comment to not reply on internal.

* Restrict downloading to safetensor files only.

* cli_args: Add --duplicate-check-hash-function.

* server.py: compare_image_hash configurable hash function

Uses an argument added in cli_args to specify the type of hashing to default to for duplicate hash checking.  Uses an `eval()` to identify the specific hashlib class to utilize, but ultimately safely operates because we have specific options and only those options/choices in the arg parser.  So we don't have any unsafe input there.

* Add hasher() to node_helpers

* hashlib selection moved to node_helpers

* default-hashing-function instead of dupe checking hasher

This makes a default-hashing-function option instead of previous selected option.

* Use args.default_hashing_function

* Use safer handling for node_helpers.hasher()

Uses a safer handling method than `eval` to evaluate default hashing function.

* Stray parentheses are evil.

* Indentation fix.

Somehow when I hit save I didn't notice I missed a space to make indentation work proper.  Oops!

* Add frontend manager

* Add tests

* nit

* Add unit test to github CI

* Fix path

* nit

* ignore

* Add logging

* Install test deps

* Remove 'stable' keyword support

* Update test

* Add web-root arg

* Rename web-root to front-end-root

* Add test on non-exist version number

* Use repo owner/name to replace hard coded provider list

* Inline cmd args

* nit

* Fix unit test

Use more explicit name 'python_module'

Parse abs ath

Move parse to nodes.py

* Fix to #3465. Prevent the, resaving of duplicate images if overwrite not specified

This is a fix to #3465 

Adds function compare_image_hash to do a sha256 hash comparison between an uploaded image and existing images with matching file names. 

This changes the behavior so that only images having the same filename that are actually different are saved to input, existing images are instead now opened instead of resaved with increment. 

Currently, exact duplicates with the same filename are resave saved with an incremented filename in the format:

<filename> (n).ext 

with the code: 

```
while os.path.exists(filepath): 
                        filename = f"{split[0]} ({i}){split[1]}"
                        filepath = os.path.join(full_output_folder, filename)
                        i += 1
```

This commit changes this to: 

```
while os.path.exists(filepath): 
                        if compare_image_hash(filepath, image):
                            image_is_duplicate = True
                            break
                        filename = f"{split[0]} ({i}){split[1]}"
                        filepath = os.path.join(full_output_folder, filename)
                        i += 1
```

a check for if image_is_duplicate = False is done before saving the file. 

Currently, if you load the same image of a cat named cat.jpg into the LoadImage node 3 times, you will get 3 new files in your input folder with incremented file names.

With this change, you will now only have the single copy of cat.jpg, that will be re-opened instead of re-saved. 

However if you load 3 different images of cats named cat.jpg, you will get the expected behavior of having:
cat.jpg
cat (1).jpg
cat (2).jpg

This saves space and clutter. After checking my own input folder, I have 800+ images that are duplicates that were resaved with incremented file names amounting to more than 5GB of duplicated data.

* fixed typo in expression

* Add TLS Support

* Add to readme

* Add guidance for windows users on generating certificates

* Add guidance for windows users on generating certificates

* Fix typo

Logging level now defaults to info. --verbose sets it to debug.

* wip per user data

* Rename, hide menu

* better error
rework default user

* store pretty

* Add userdata endpoints
Change nodetemplates to userdata

* add multi user message

* make normal arg

* Fix tests

* Ignore user dir

* user tests

* Changed to default to browser storage and add server-storage arg

* fix crash on empty templates

* fix settings added before load

* ignore parse errors

A POST request to /free with: {"unload_models":true}
will unload models from vram.

A POST request to /free with: {"free_memory":true}
will unload models and free all cached data from the last run workflow.

If an error occurs while retrieving object_info, only the node that encountered the error should be handled as an exception, while the information for the other nodes should continue to be processed normally.

Try to prevent JS search from breaking on pathnames with square
brackets.

Co-authored-by: Lt.Dr.Data <lt.dr.data@gmail.com>