Custom Action support

See merge request gitlab-org/gitlab-ce!21034

Port changes for CODEOWNERS to CE

See merge request gitlab-org/gitlab-ce!21309

Enable Kubernetes RBAC for GitLab Managed Apps for existing clusters

See merge request gitlab-org/gitlab-ce!21127

Fix usage statistics typo documentation

See merge request gitlab-org/gitlab-ce!21555

Resolve "Update presentation for SSO providers on log in page"

Closes #44943

See merge request gitlab-org/gitlab-ce!21233

Explicit hashed path check for trace, prevents background migration from…

See merge request gitlab-org/gitlab-ce!21533

- Use proper HTTP codes for /api/v4/allowed response
- CustomAction support

- if #check_custom_action!(cmd) returns something, return from #check()
- now returns :Gitlab::GitAccessResult::Success.new instead of true

Add User-Agent to production_json.log

See merge request gitlab-org/gitlab-ce!21546

Update user markdown documentation for CommonMark

See merge request gitlab-org/gitlab-ce!21509

Enable CommonMark for files and wikis

See merge request gitlab-org/gitlab-ce!21228

Fix LineBreakAroundConditionalBlock cop for a conditional after rescue

See merge request gitlab-org/gitlab-ce!21535

Resolve "Improve project overview UI"

Closes #44704

See merge request gitlab-org/gitlab-ce!20536

This ports the changes for the CODEOWNERS feature to CE:
- It adds the CODEOWNERS file.
- It adds the mention of the `with-codeowners` branch in TestEnv

Upgraded Monaco editor version

See merge request gitlab-org/gitlab-ce!21526

CE backport of changes that introduce custom instance-level templates to EE

See merge request gitlab-org/gitlab-ce!21530

Bump browser gem to v2.5.3

See merge request gitlab-org/gitlab-ce!21547

Full list of changes: https://github.com/fnando/browser/blob/master/CHANGELOG.md

This will help production gain more visibility which browsers may be
having issues.

Add route information to lograge structured logging for API logs

Closes #50993

See merge request gitlab-org/gitlab-ce!21487

Fix documentation on upgrading when using a Helm chart

See merge request gitlab-org/gitlab-ce!21539

Add support for advanced CI/CD config extension with `extends:`

Closes gitlab-ee#6136

See merge request gitlab-org/gitlab-ce!21243

Fix multipart error on rails reload

See merge request gitlab-org/gitlab-ce!21540

remove comma

See merge request gitlab-org/gitlab-ce!21536

Merge branch '45938-postgres-timeout-when-counting-number-of-ci-builds-for-usage-ping' into 'master'

Resolve "Postgres timeout when counting number of CI builds for usage ping"

Closes #45938

See merge request gitlab-org/gitlab-ce!21523

Document that when updating using a Helm chart 'helm repo update' needs to be run before the 'helm upgrade ...' command.