This changes how we link merge requests to deployments so that:

1. We link merge requests for any deployment that is not in the
   "created" state.
2. We do not link merge requests to review app deployments.

We want to link deployments regardless of their status so that we can
also show failed and running deploys in the merge request widget (and
perhaps in other places). We don't want to link review app deployments
since this is not useful, and may lead to deployments to different
review app environments showing up on a merge request page.

This builds on the refactoring of the deployment model introduced in
merge request https://gitlab.com/gitlab-org/gitlab/merge_requests/20474,
and moves the linking of merge requests to Deployments::FinishedWorker.
This worker is scheduled every time a deployment transitions to a
finished state.

As part of these changes we also change Deployment#link_merge_requests
so that it ignores any already linked merge requests. This way if a
deployment changes its status multiple times, we don't error with
duplicate key errors.

This fixes https://gitlab.com/gitlab-org/gitlab/issues/38092.

Add Index to help Hashed Storage migration on big instances

Closes #194066

See merge request gitlab-org/gitlab!22391

Use proper find targets in test

Closes #191269

See merge request gitlab-org/gitlab!22298

Wrap requests in an ApplicationContext

See merge request gitlab-org/gitlab!20791

Performance improvements on milestone burndown chart

See merge request gitlab-org/gitlab!22380

Prevent Gitaly N+1 queries in blob search

See merge request gitlab-org/gitlab!21996

Remove ActiveRecord patch to ignore limit on text columns

See merge request gitlab-org/gitlab!22406

Wrap emit calls to nextTick

Closes #38114

See merge request gitlab-org/gitlab!22323

Don't build up events array when checking if burndown chart
is empty or accurate. Preload issue project to avoid N+1 calls.

This provides context to all requests made to Rails controllers or
grape endpoints.

Doing this starts a new `Labkit::Context`, to which we can provide a
namespace, project and user.

We're currently setting the following values:

- Web requests: In the ApplicationController we wrap the entire
  request in a `with_context`.
  - user: based on the `auth_user` if there is one
  - project: We try to read the @project instance variable of the
    controller.
  - namespace: We try to read the @group instance variable of the
    controller. If there was none, but the project was set, we'll use
    that path to set the namespace

- API requests: The application context is pushed in a before block
  setting the following values:
  - user: to `current_user` if there is one
  - project: to `@project`
  - namespace: to `@group`

- Internal API requests: the application context is pushed in a before
  block:
  - user: When to the user set in `Api::Support::GitAccessActor`
  - project: to @project if it was available

The 3 supported attributes for a context are read lazily when
required.

This also replaces the existing correlation middlewares with the new
Labkit::Context middlewares.

The rack middleware wraps each rack request in an overarching context
that adds the correlation id. The context is cleaned up after the
request, so we're sure all child contexts are cleaned up as well.

The sidekiq client middleware will write the context into the job that
 goes into redis when a job is scheduled.

The sidekiq server middleware will then re-instantiate this context so
the job gets executed with the same context that was alive when it was
scheduled. This means that any new job scheduled from sidekiq would
also have this context.

This makes sure we're always working with the project that we've
validated access for.

Add Reenqueuer concern

See merge request gitlab-org/gitlab!22031

Add system/comment filter to notes api

See merge request gitlab-org/gitlab!21159

Add logging to error handling in ElasticIndexerWorker

See merge request gitlab-org/gitlab!22414

Add explanation to the "programming languages used" chart

See merge request gitlab-org/gitlab!20592

Create downstream pipeline inside same project

See merge request gitlab-org/gitlab!20930

Feature for #27518, users can revoke active sessions again.

Closes #27518

See merge request gitlab-org/gitlab!17462

Fix typo in CI yaml docs

See merge request gitlab-org/gitlab!22382

Prevent spiders indexing contribution analytics

See merge request gitlab-org/gitlab!21896

Resolve "Auto stop environments after a certain period"

See merge request gitlab-org/gitlab!20372

Add #finding method to Vulnerability

See merge request gitlab-org/gitlab!22346

Setup multiple milestones

See merge request gitlab-org/gitlab!22043

Update foreign key constraint for personal access tokens

Closes #191262

See merge request gitlab-org/gitlab!22305

Docs: Remove duplicate deploy action from aws.md

See merge request gitlab-org/gitlab!22365

Use Ruby 2.6.5 CI images

See merge request gitlab-org/gitlab!22372

This is intended to help hashed storage migration on big instances.

fix include template code examples for SAST

See merge request gitlab-org/gitlab!22339

Update github import test

Closes #193485

See merge request gitlab-org/gitlab!22353

It needs to click the authenticate button, and then the repos are listed

Docs: Remove extraneous text

See merge request gitlab-org/gitlab!22403

This was fixed upstream in https://github.com/rails/rails/pull/8276,
in Rails 3.2.13 (Mar 18, 2013).

Replace breakpoints with GlBreakpointInstance in issuable_context.js

See merge request gitlab-org/gitlab!22008

This is the commit for all changes, for merging

This change involves both HAML and Vue, plus refactoring

Check that uploaded file content matches the file extension

See merge request gitlab-org/gitlab!20697

Handle when extension is missing
Handle ambiguous file type checks
- Content of text files often don't define their type.
- A text file may be missing a file extension.
- We may encounter a file with no extension that we can't magically
type.
Optionally check integrity of specific mime types
Ensure upload integrity by file extension
Apply integrity check to AvatarUploader and FaviconUploader