Currently, we have markdown files in many places (e.g. comments, new
issues, etc.). This Merge Request detects if the file being edited is a
markdown file and adds markdown buttons and their functionality to the
single file editor (Not the web IDE)

Signed-off-by: NTakuya Noguchi <takninnovationresearch@gmail.com>

Remove jquery.scss; Combine multiple duplicate grays into global gray variables; Remove unused styles in common.scss

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/39497

Fixing some preexisting issues (Safari) and some new issues (Windows
Firefox)

Adds MR ID to changelog entry

Removes changelog entry

Fixes after review

adds entry in CHANGELOG

no uninitialized variable and unnecessary if statement

formatting issue in CHANGELOG

resolves scss lint warings

cleanup: unnecessary css classes

adds css class that cleaned up by mistake

replaces snake_case variables name with camelCase

removes unnecessary css class and adds white color border for avatar

moves changelog entry from 8.13 to 8.14

remove bottom margin from avatar-inline

resolves lint warnings

rebased and moves changelog entry to 8.14

fixes avatar shifting on hover

adds entry at top of 8.14 section in CHANGELOG.md

calls sanitization for gl.utils

syncing changelog with master and created changelog files using cli

changes changelog title

Some important things to note:

- commands are removed from noteable.description / note.note
- commands are translated to params so that they are treated as normal
  params in noteable Creation services
- the logic is not in the models but in the Creation services, which is
  the right place for advanced logic that has nothing to do with what
  models should be responsible of!
- UI/JS needs to be updated to handle notes which consist of commands
  only
- the `/merge` command is not handled yet

Other improvements:

- Don't process commands in commit notes and display a flash is note is only commands
- Add autocomplete for slash commands
- Add description and params to slash command DSL methods
- Ensure replying by email with a commands-only note works
- Use :subscription_event instead of calling noteable.subscribe
- Support :todo_event in IssuableBaseService
Signed-off-by: NRémy Coutable <remy@rymai.me>