Client Implementation: RefService::RefExists

Closes gitaly#452

See merge request !13528

Fix unnecessarily long gl.utils.backOff test

Closes #36648

See merge request !13651

Add support for i18n on Project Activity Page

Closes #32795

See merge request !13451

Setup settings properly

See merge request !13645

Don't escape html entities in InlineDiffMarkdownMarker

Closes #36041

See merge request !13553

Gitaly apply gitattributes

Closes gitaly#464

See merge request !13517

Updates for proper obj notation.

See merge request !13430

API: do not set rel="next" pagination header when no records found

Closes #36618

See merge request !13629

Fix external link to Composer website

Closes #36611

See merge request !13621

Make admin user actions dropdown consistent

See merge request !13630

Fixes the blown up emoji problem in notes

Closes #36448 and #36282

See merge request !13632

Properly explain when advanced Docker options were introduced

See merge request !13608

Docs: article - "Numerous undo possibilities in Git"

Closes gitlab-com/community-writers#40

See merge request !13513

And the link to the last page cannot be `page=0`.

Add specs that check the 'Link' header for the inclusion of:

 - rel="first"
 - rel="last"
 - rel="prev"
 - rel="next"

Fixes gitlab-org/gitlab-ce#36618

Related to gitlab-com/infrastructure#2532

Merge branch 'master' into 'docs-article-undo-things-in-git'

# Conflicts:
#   doc/articles/index.md

Move workflow/importing/ to user/project/import/

See merge request !13593

Prevent horizontal scrolling in new sidebar when collapsed

Closes #36608 and #36507

See merge request !13638

Allow all users to delete their account

Closes #36087

See merge request !13636

Backports EE mirror stuck handling feature…

See merge request !13627

Use grpc 1.4.5

Closes gitaly#468

See merge request !13597

Previously the user could not delete his own account unless signup was
enabled in the global settings. This was due to the fact that deleting
the user would also delete the issues and other items associated to him.
Deleting an user does not destroy essential data anymore, for this
reason we removed the `signup_enabled?` check.

Backports EE mirror stuck handling feature (https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2628) to CE

Fixed height of group share dropdown

Closes gitlab-ee#3149

See merge request !13505