Remove old navigation CSS

See merge request gitlab-org/gitlab-ce!14573

Fix LDAP config key name

See merge request gitlab-org/gitlab-ce!14739

Create idea of read-only database

Closes #37534

See merge request gitlab-org/gitlab-ce!14688

Create merge requests across a fork network

Closes #20097

See merge request gitlab-org/gitlab-ce!14422

So we can keep showing it to a user in his project page.

This uses the existing ForkedProjectLinks

The helper creates a fork of a project with all provided attributes,
but skipping the creation of the repository on disk.

When no fork network exists for the source projects, we create a new
one with the correct source

The fork network will keep track of the root project as long as it's
present.

Add CI build trace sections extractor

Closes #37970

See merge request gitlab-org/gitlab-ce!14511

# Conflicts:
#   db/schema.rb

Commenting on image diffs

Closes #35873 and #38559

See merge request gitlab-org/gitlab-ce!14061

Backport protected_branches_spec improvements from EE

See merge request gitlab-org/gitlab-ce!14745

Removes unnecessary load of LinkedTabs, Pipelines and MiniPipelineGraph classes

See merge request gitlab-org/gitlab-ce!14734

Resolve "Metrics that do not have a complete history are not shown at all"

Closes #36255

See merge request gitlab-org/gitlab-ce!14741

Show confirmation modal before deleting account

Closes #13482 and #38754

See merge request gitlab-org/gitlab-ce!14360

In GitLab EE, a GitLab instance can be read-only (e.g. when it's a Geo
secondary node). But in GitLab CE it also might be useful to have the
"read-only" idea around. So port it back to GitLab CE.

Also having the principle of read-only in GitLab CE would hopefully
lead to less errors introduced, doing write operations when there
aren't allowed for read-only calls.

Closes gitlab-org/gitlab-ce#37534.

* master: (136 commits)
  Ensure we set SUITE_FLAKY_RSPEC_REPORT_PATH to nil in RspecFlaky::Listener spec
  Gitaly feature flag metadata
  Add delete issue docs
  Adjust tooltips to adhere to 8px grid and make them more readable
  Fix JS lock issue specs
  Improve redirect uri state and fix all remaining tests
  Add 1000+ counters (instead of inifnite) to jobs controller
  Use short path project_clusters_url
  Change Clusters to Cluster in sidebar
  Security fix: redirection in google_api/authorizations_controller
  UX review
  Fix sidebar title Fix fixture
  Fix margins in edit form
  Use utc for time comparision
  Good old dangling comma
  Fix wording in the js messages
  Resetting of active Line + setting it for the async display functions
  Add some empty spaces
  Fix failing spec
  Refactor discussion lock docs
  ...