Automatic loading of packages from zap files. (#806)

* Remove a bunch of useless logic for loading validator.

* Clean up some mess of package loading, removing session where it is not needed.

* Update negative case.

* Fix the devserver execution for cypress.

* Make packageMatch a non-boolean option.

* Implement autoloading properly.

* Add a package matching mode which simply ignores the packages in zap file, used in unit tests.

* Clean up a unit test.

* Fix the matter test file to no longer point to zigbee.

* Simplify the analyze script.

* Update the template loader to not try to reload package options.

* Update docs.

* Clean up a comment.

* Remove unused argument.