correctly scroll to element with sticky height offset

added specs to sticky util file
added `No files found.` text when results are empty

This makes navigating through diff files quickly. Currently we just
toggle a list, which could be pretty big. This moves it into a dropdown
to make it much easier.

Also includes a filter bar to quickly search for certain
files/extensions.

Closes #29778

Fixed sign-in restrictions buttons not toggling active state

Closes #35882

See merge request !13270

Migrate Gitlab::Git::Repository#count_commits to Gitaly

Closes gitaly#415

See merge request !13121

Merge request commits background migration

See merge request !12685

Move API "basic usage" to be more visible

See merge request !13171

Update reply_by_email_postfix_setup.md, included starting courier-authdaemon after installation.

See merge request !13218

fix Jump to next discussion

Closes #35232

See merge request !13076

Make dropdown style on project page consistent

Closes #35778

See merge request !13193

Don't send rejection mails for all auto-generated mails

Closes #28472

See merge request !13254

Previously, we stored these as serialised fields - `st_{commits,diffs}` - on the
`merge_request_diffs` table. These now have their own tables -
`merge_request_diff_{commits,diffs}` - with a column for each attribute of the
serialised data.

Add a background migration to go through the existing MR diffs and migrate them
to the new format. Ignore any contents that cannot be displayed. Assuming that
we have 5 million rows to migrate, and each batch of 2,500 rows can be
completed in 5 minutes, this will take about 7 days to migrate everything.

Ensure we run installation Rake tasks in a clean env in TestEnv

Closes #35859

See merge request !13249

This would be much more accurate. We assume this is an
auto-generated email if such header is provided, and
the value is not "no". It could also be: "auto-generated",
"auto-replied", or other values from extension. It seems
that only "no" could mean that this is sent by a human.

See: https://tools.ietf.org/html/rfc3834

Closes #35882

Do not validate CSRF token in API unless needed

Closes #35705

See merge request !13256

Remove test gitaly when older than version file

See merge request !13250

Fly-out dropdown menu in new sidebar

Closes #34026

See merge request !12938

Fix Prometheus application settings help link to point to Prometheus help page

Closes #33921

See merge request !13258

Disable the Rails/Delegate cop

Closes #35869

See merge request !13267

Empty project factory by default

See merge request !13260

See https://gitlab.com/gitlab-org/gitlab-ce/issues/35869 for the
rationale.
Signed-off-by: Rémy Coutable <remy@rymai.me>

Change project FK migration to skip existing FKs

Closes #35243

See merge request !13235

Signed-off-by: Rémy Coutable <remy@rymai.me>

If we call `system('rake', 'taks_name')`, `ENV['RUBYOPT']` is set to
`'-rbundler/setup'` but some tasks (e.g. `gitlab:gitaly:install` need
a clean env since they install their own Gem bundle.
Signed-off-by: Rémy Coutable <remy@rymai.me>

Also make it easier to have mailer helper