Override the `ApplicationSetting` default visibility_level setters so
they accept strings & integers for the levels.

Add `visibility` & `visibility=` methods to the
`Gitlab::VisibilityLevel` module so the `visibility_level` can be
get/set with a string value.

And add changelog entry.

Use strings for the ApplicationSetting properties:
 - restricted_visibility_levels
 - default_project_visibility
 - default_snippet_visibility
 - default_group_visibility

Because environments also expose the project, ensure the projects are
exposed as they were before in API v3.

Instead of exposing the VisibilityLevel as Integer, expose it as
String `visibility`.

Instead of exposing the VisibilityLevel as Integer, expose it as
String `visibility` for Project and ProjectSnippet.

Filter queries also accept the `visibility` as String instead of
`visibility_level` as Integer.

Also remove the `public` boolean.

For the API, the VisibilityLevel will be exposed as String instead of
Integer. So add the string values and method to translate a level
integer to a string.

Add internal endpoint to notify post-receive to Gitaly

See merge request !8983

Fix ES6 interpolation in GitLabCrop class

Closes #28647

See merge request !9624

Use v4 endpoint in API docs

See merge request !9631

Rename MWBS to MWPS

Closes #24707

See merge request !9335

Improve internal API for new merge request

Closes #27866

See merge request !9304

API: Add environment action with /stop action

Closes #27142

See merge request !8808

Remove unused method from CI/CD build class

See merge request !9615

Persona images

See merge request !9556

remove duplicate backup skip details

See merge request !9525

fix GitLab download archives link

See merge request !9528

Clarification of list repository tree API call

Closes #26136

See merge request !9532

Improve a11y in sidebar

Closes #27778

See merge request !9593

Fix the redirect to custom home page URL and move it to RootController

Closes #28609

See merge request !9518

Add changelog for !9614

See merge request !9626

Add RuboCop cop for custom error classes

Closes #28770

See merge request !9573

Fixed long filename being under action buttons

Closes #26607

See merge request !9608

Remove the newrelic gem

Closes #12860

See merge request !9622

Removed top border from contribution calendar

Closes #28844

See merge request !9605

The frontend should use the v3 API for now

Closes #28863 and #28853

See merge request !9614

Visually display that expanded diff lines cant be commented on

See merge request !9465

Add view specs for CI/CD detailed status badge

Closes #25611

See merge request !9473

Disable the inheritance column of services in DisableInvalidServiceTemplates migration

Closes #28850

See merge request !9613