Add support for showing HTML comments in rich text editor as
a placeholder element.

Changelog: added

IEC 61131-3 Structured text is a programming language for PLCs
(programmable logic controllers) used within the automation domain

Changelog: added

Allow referenceing group level work items by
URL or references (short, long)

This uses `comrak` support to parse wiki links.

Changes URLs to markdown uploads to use project / group IDs instead of
project / group paths

Can now use the native support in the markdown parser

Changelog: fixed

Changed: changed

Supports both dollar math and code/GitLab math
syntax. Fixes an entire set of bugs with math parsing.

Changelog: fixed

Changed: fixed

Add support for autocompleting wiki pages in other wiki pages,
issues, epics, MRs and work items.

- This MR Adds autocomplete support for Wiki pages in other
wiki pages and issues using the `[[` shortcut.
- Issues in projects can now autocomplete links to project
wiki pages.
- Epics can autocomplete links to group wiki pages.
- You can search for pages by title to find the doc page you want.

Notes:

- On group level items like epics and group level work items,
you can only autocomplete group level wiki pages. (EE only)
- On project level items like issues, MRs and project level work
items, you can only autocomplete wiki pages in the same project.

Changelog: added

Until now, copy_as_gfm feature used its own serializer to copy content
as markdown. Since content editor also has its own serializer, we remove
the serializer in use in copy_as_gfm and use the one in content editor
instead.

Changelog: changed

In rich text editor, add support for rendering inapplicable task items from markdown content
in the plain text editor.

Changelog: added

Uses the gem `gitlab-glfm-markdown`, which interfaces with
the Rust markdown parser `comrak`

Changed: other

Add support for aligning columns left, right and center in the rich text editor

Changelog: added

passed bullet attribute in task_list and added tests

Changelog: changed

In the spirit of WYSIWYG, we now disable rendering HTML comments
completely in the content editor.

Changelog: changed

- Do not render class attribute as it could render in unexpected ways,
which aren't supported when real markdown is rendered.
- Strip any stray div, span or pre tags in pasted HTML before paste

Changelog: fixed

The update in libxml2
(https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.11.0) stopped
escaping ASCII characters in HTML:
https://gitlab.gnome.org/GNOME/libxml2/-/issues/321. Update the
specs and Markdown snapshot accordingly.

Set the libxml2 memory allocator via
`NOKOGIRI_LIBXML_MEMORY_MANAGEMENT=default` to work around Ruby
interpreter bug. This variable can be dropped once
https://github.com/ruby/ruby/pull/7663 ships with a Ruby interpreter
that is used.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/390313

Changelog: changed

Allow new data-footnote-backref-idx attribute

Changelog: changed

Render dir="auto" in all content editor extensions to automatically
support RTL.

Changelog: added

Changelog: changed

in order to move away from using the `lang` attribute

Merge branch 'security-update-glfm' into 'master'

See merge request gitlab-org/security/gitlab!3166

Changelog: security

See https://github.com/rouge-ruby/rouge/pull/1920/files#diff-9f8f9240d5f153287f6420c9c9d20af2edcf1286c8ee7573c6d1d297598a9203 for more details.

Changelog: added

Fixes a situation where a user name ending with `_`
and refernced with `\_` during autocomplete
would not be properly detected.

Changelog: fixed

to better handle escaping characters

Changelog: changed

to handle additional characters

Added two test cases - one with empty `langParams` and
the other with colon followed by `langParams`

Changelog: added

- Converts GitLab Flavored Markdown Examples from old
  Golden Master approach to new approach.

Add support for rendering and editing HTML comments in the comments in
the content editor.

Changelog: added