Allow getting the merge base of multiple revisions

Closes #52573

See merge request gitlab-org/gitlab-ce!22295

Add documentation how to assign a merge request for review

See merge request gitlab-org/gitlab-ce!21327

Remove dependencies on Linguist

Closes #35450

See merge request gitlab-org/gitlab-ce!21008

Refactor Cluster services to enable groups or projects

See merge request gitlab-org/gitlab-ce!22181

Fixes close/reopen quick actions preview for issues and merge_requests

Closes #52669

See merge request gitlab-org/gitlab-ce!22343

Fix code reuse issue in Projects::Clusters::ApplicationController#index

See merge request gitlab-org/gitlab-ce!22182

Merge branch '49417-improve-settings-pages-design-by-prioritizing-content-group-settings' into 'master'

Prioritize group settings, improve panel titles, disable submit without changes

Closes #49417

See merge request gitlab-org/gitlab-ce!21115

Resolve "Personal projects pagination in Profile Overview tab is broken"

Closes #52564

See merge request gitlab-org/gitlab-ce!22321

[ci skip]

Send deployment_status when job starts environment

Closes #52614

See merge request gitlab-org/gitlab-ce!22354

Use Gitaly 0.125.1

See merge request gitlab-org/gitlab-ce!22364

The check was if the job `has_environment` which results into showing
the environment information when the job stops the environment. This
result into having a blank `deployment_status`.

Use `starts_environment?` to be the same as the haml we have in 11.3
https://gitlab.com/gitlab-org/gitlab-ce/blob/30f019dca78bb64bcb8b355a267be006884e6d8f/app/views/projects/jobs/show.html.haml#L28

Docs: fix table on API settings

Closes gitlab-com/gitlab-docs#234

See merge request gitlab-org/gitlab-ce!22083

Update docs maintenance upgrade path examples

See merge request gitlab-org/gitlab-ce!22360

Adjust link to docs development guide

See merge request gitlab-org/gitlab-ce!22288

Improve the contributing documentation

See merge request gitlab-org/gitlab-ce!22291

Close/reopen quick actions preview wasn't shown properly, now the
preview is shown as expected.

Add GitLab QA spec for adding a deploy token

See merge request gitlab-org/gitlab-ce!22207

Backport CE changes for: Resolves "Reviews: Resolving or unresolving discussions with “Add comment now” does not work"

See merge request gitlab-org/gitlab-ce!22303

Improve spec for Gitlab::Ci::Status::Pipeline::Factory

Closes #52280

See merge request gitlab-org/gitlab-ce!22247

Enable some frozen string in lib/gitlab

See merge request gitlab-org/gitlab-ce!22304

Resolve "Show canary / no-canary in the performance bar"

Closes #52421

See merge request gitlab-org/gitlab-ce!22222

Only display merge commit SHA when it exists

Closes #48889

See merge request gitlab-org/gitlab-ce!22022

Update Android.gitlab-ci.yml for current stable SDK

See merge request gitlab-org/gitlab-ce!22336

Docs: Link to DeclarativePolicy framework from development guide

See merge request gitlab-org/gitlab-ce!22348

Docs: Fixing some bad links

See merge request gitlab-org/gitlab-ce!22287

Remove the inheritance from ::BaseService which is causing us to inherit
the initializer that has project as the first arg, as we will not have
access to project with forthcoming group clusters.

Also call install service from create service - 1 less thing to re-use

Extract TestRequest code into a spec helper. Given that we need
different behaviour for Rails 5.0 (and again in Rails 5.1!), it's handy
to have that branching behaviour in one place

This should help with code re-use when we create applications for group
level cluster next.

Change `find_or_initialize_by` to explicitly find or build the right
association based on the application name. The benefit here is that we
use the associations on @cluster rather than querying from the other
side of the association.

This enables us to have other options in the future such as passing in
`group:`.

Also, remove project arg from UpdateService, as un-used.

This will help group cluster controller to re-use this services.

Fix duplicated key in license management job gitlab-org/gitlab-ce#52609

Closes #52609

See merge request gitlab-org/gitlab-ce!22311