This removes the `ForkedProjectLink` model that has been replaced by
the `ForkNetworkMember` and `ForkNetwork` combination. All existing
relations have been adjusted to use these new models.

The `forked_project_link` table has been dropped.

The "Forks" count on the admin dashboard has been updated to count all
`ForkNetworkMember` rows and deduct the number of `ForkNetwork`
rows. This is because now the "root-project" of a fork network also
has a `ForkNetworkMember` row. This count could become inaccurate when
the root of a fork network is deleted.

[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

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

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

Closes #52609

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

Enable frozen string for the following files:

* lib/gitlab/auth/**/*.rb
* lib/gitlab/badge/**/*.rb
* lib/gitlab/bare_repository_import/**/*.rb
* lib/gitlab/bitbucket_import/**/*.rb
* lib/gitlab/bitbucket_server_import/**/*.rb
* lib/gitlab/cache/**/*.rb
* lib/gitlab/checks/**/*.rb

Partially addresses #47424.

Fix rubocop complaining about unicorn.rb

See merge request gitlab-org/gitlab-ce!22332

Update merge request diff navigation docs

See merge request gitlab-org/gitlab-ce!22275

Drop support for Go 1.9 in GitLab 11.4

Closes #51982

See merge request gitlab-org/gitlab-ce!22324

Updates the check for started in job header

See merge request gitlab-org/gitlab-ce!22329

Add stage name in job.json response

Closes #52618

See merge request gitlab-org/gitlab-ce!22317

The function that was checking if the job was started or not
was expecting a boolean, however it was receiving a null.
During the refactor the condition was changed, causing the function
to break with null

This commit fixes the check

Fix the event API docs

Closes #52512

See merge request gitlab-org/gitlab-ce!22320

Backport CE changes for Ops Dashboard in EE

See merge request gitlab-org/gitlab-ce!22136