Fix diffs with edit-forking needs -- EE merge edition

Closes gitlab-ce#31276 and gitlab-ce#30637

See merge request !1705

Bump mysql2 gem from 0.3.16 -> 0.4.5

See merge request !1715

Merge branch 'master' of gitlab.com:gitlab-org/gitlab-ee into ee-31276-fix-diffs-with-edit-forking-needs

Conflicts:
	app/assets/javascripts/blob/blob_fork_suggestion.js
	app/assets/javascripts/dispatcher.js
	spec/javascripts/blob/blob_fork_suggestion_spec.js

Use jQuery niceness on blob_fork_suggestion -- EE merge edition

See merge request !1706

Fix incorrect spec filenames which were ingored by CI

Closes #2250

See merge request !1709

Refactor deploy boards into vue files

See merge request !1694

Appears to fix some issues in Timeout: https://github.com/brianmario/mysql2/releases

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/31276

Conflicts:
	app/views/projects/blob/_header.html.haml

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/30637

Added info about Admin user ability to push to protected branches.

See merge request !1009

Test both PostgreSQL and MySQL for the win

See merge request !1646

* Add Audit events link to project settings tab and make audit tests work
* Fix 404 when remove deploy key
* Fix pipelines quota specs
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Make handler metric params more explicit

See merge request !1696

Refactor add_users method for project and group [EE]

See merge request !1697

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

This lets us track how many incoming emails a GitLab instance is processing, by
email type (handler) and by project (where applicable).

Remove duplicated tests

See merge request !1687

Fix
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10602#note_27871752

Conflicts:
	app/assets/javascripts/blob/blob_fork_suggestion.js
	app/assets/javascripts/dispatcher.js
	spec/javascripts/blob/blob_fork_suggestion_spec.js

[ci skip]

[ci skip]

Docs for canary deployments vol 2

Closes gitlab-ce#31270

See merge request !1704

[ci skip]

Replace service_desk_enabled.png

See merge request !1701

Docs for resolvable discussions

See merge request !1700

Check if incoming emails and email key are available for service desk

Closes #2160

See merge request !1690

- Move to dicsussions/index.md
- Bring back previous path with a link to new location
- Reorder sections