Avoid error when creating forks and restricted levels are defined

Closes #42607

See merge request gitlab-org/gitlab-ce!16881

use Gitlab::UserSettings directly as a singleton instead of including/extending it

Closes #37698

See merge request gitlab-org/gitlab-ce!16843

More conversions to axios

See merge request gitlab-org/gitlab-ce!16800

Improve top area navigation

See merge request gitlab-org/gitlab-ce!16726

Resolve "Incorrect merge request title when Jira activated and multiple commits on branch"

Closes #40793

See merge request gitlab-org/gitlab-ce!16491

Reload source MRs memoization after diffs creation

Closes #42668

See merge request gitlab-org/gitlab-ce!16868

- Change button group width on mobile to 100%
- Added scrolling container to activity top area secondary navigation
- Added bottom border to top-area nav-links to separate them from nav-controls

Backport of mr_widget_author.vue EE changes

See merge request gitlab-org/gitlab-ce!16884

Replace $.ajax in project.js

See merge request gitlab-org/gitlab-ce!16873

Resolve "Sign-in page logo is not properly rendered."

Closes #42695

See merge request gitlab-org/gitlab-ce!16875

Add unique constraint to trending_projects#project_id.

See merge request gitlab-org/gitlab-ce!16846

Resolve "GitLab import leaves `group_id` on ProjectLabel"

Closes #42696

See merge request gitlab-org/gitlab-ce!16877

Port of gitlab-ee!3867 to CE

See merge request gitlab-org/gitlab-ce!16775

When no visibility levels are defined they could sometimes return
`nil` instead of an empty array. In this case we want to allow all
levels.

# Conflicts:
#   db/schema.rb

Fix an issue where sparse checkout wasn't configured correctly

See merge request gitlab-org/gitlab-ce!16864

Moves more mr widget components into vue files

See merge request gitlab-org/gitlab-ce!16857

Moves author components into vue files

See merge request gitlab-org/gitlab-ce!16863

Fix typo in gitlab_runner_chart.md

See merge request gitlab-org/gitlab-ce!16860

Finish any remaining jobs for issues.closed_at

Closes #41595

See merge request gitlab-org/gitlab-ce!16858

Improve issue note dropdown and mr button

See merge request gitlab-org/gitlab-ce!16758

QA::Page::Component::Dropzone#initialize needs a QA::Page::Base object

See merge request gitlab-org/gitlab-ce!16852

Ensure we save QA screenshots to an absolute path

See merge request gitlab-org/gitlab-ce!16845

Backport changes in the application settings helper to CE

See merge request gitlab-org/gitlab-ce!16801