Fixes #60552

Autocompletion for references happens on the frontend. Those references
are turned into actual references on the backend, but only after
Markdown processing has happened. That means that if a reference
contains a character that Markdown might consume, it won't render
correctly. So we need to do some escaping on the frontend.

We have these potential problem characters:
https://docs.gitlab.com/ee/user/markdown.html#emphasis

1. ~ - this is ~~strikethrough~~, but only when doubled.
2. _ - used for _emphasis_, doubled is __bold__.
3. * - also used for *emphasis*, doubled is **bold** also.
4. ` - used for `code spans`, any number works.

We don't need to escape `-` any more. When it comes to being inside a
word:

1. a~~b~~ has strikethrough, so it needs to be escaped everywhere.
2. a_b_ has no emphasis (see [a]) so it only needs to be escaped at the
   start and end of words.
3. a*b* has emphasis, so it needs to be escaped everywhere.
4. a`b` has a code span, so it needs to be escaped everywhere.

Or, in code terms:

1. Always escape ~~, *, and ` when being inserted by autocomplete.
2. Escape _ when it's either at the beginning or the end of a word.

[a]: https://docs.gitlab.com/ee/user/markdown.html#multiple-underscores-in-words

Reverts the loading of emojis and its images to move forward with RC

Created new emojis map in public folder

Renamed folder to emojis

Loading now the emojis from Localstorage or from Server

Moved all emojis to the public folder

Loading the emojis.json file now through AJAX

Loads now the map in the web element instead when building the emoji tag

Updated the custom Element Setup to modern method

Fixed Emoji Karma Specs for async loading

Loading now the emojis from Localstorage or from Server

Loads now the map in the web element instead when building the emoji tag

Fixed problem with FIXTURE_PATH for emojis fixtures

Fixes Linting Error in gemojione.rake

Fixed Emoji Karma Specs

Fix static type check in gemojione and check if already registered

Testing if the Emoji Support Check is failing Rspec

Change of CLass Name, returning true on check to test

Fixes failing Emoji RSpec Tests

Moved Emojis into public/-/emojis/1/

Fixed Linting Errors in gl_emoji

Fix to fixtures creation for emojis

Fixed path spec for new subdirectory -/emojis

Optimized emojis.json output

Fix for Emoji Spec failure due to unicode dataset

Better catch handling for emojis

- Add rectangular avatar classes
- Update avatar for groups
- Update avatar for projects
- Update avatar for frequent items
- Update avatar on "Fork project" page
- Conditionally add rectangular avatar class to autocomplete items

Currently not used by any CE code