Add new emoji icons
Remove added SVGs
Change to sprite_icons
Prettify
Fix text left behind
Fix errors
Remove background top level reaction icon

This prevents performing the requests, and disables all emoji reaction buttons

Removes the text `Handle with care` as it sounds condescending.

also fix some code styling issues

 - only show in merge-requests
 - show as a little glyph

this will remove the need make N queries (per-note) at the
cost of having to mark notes with an attribute

this opens up the possibility for other special roles for notes

a new badge will be added when an user that doesn't yet
have any merged merge request is discussing on either issues or
merge requests that he created.

this is indented for people to use extra care when discussing with
a new contributor.

[ci skip] Correct rendering more actions dropdown when there are no actions and correct the more actions dropdown divider conditional

Update _more_actions_dropdown.html.haml to only show 'Edit comment' when user is allowed to edit the note and only show 'Report as abuse' when the note doesn't belong to current_user

Remove slash commands from Markdown preview and display their outcome next to
the text field.
Introduce new "explanation" block to our slash commands DSL.
Introduce optional "parse_params" block to slash commands DSL that allows to
process a parameter before it is passed to "explanation" or "command" blocks.
Pass path for previewing Markdown as "data" attribute instead of setting
a variable on "window".

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/30810