- Refactor uploads manager
- Refactor importer, update import spec
- Add more object storage specs

Automatically expand runner's settings block when linking to the runner's settings page by using page anchor on the link

Our friends at GitHub show the programming languages for a long time,
and inspired by that this commit means to create about the same
functionality.

Language detection is done through Linguist, as before, where the
difference is that we cache the result in the database. Also, Gitaly can
incrementaly scan a repository. This is done through a shell out, which
creates overhead of about 3s each run. For now this won't be improved.

Scans are triggered by pushed to the default branch, usually `master`.
However, one exception to this rule the charts page. If we're requesting
this expensive data anyway, we just cache it in the database.

Edge cases where there is no repository, or its empty are caught in the
Repository model. This makes use of Redis caching, which is probably
already loaded.

The added model is called RepositoryLanguage, which will make it harder
if/when GitLab supports multiple repositories per project. However, for
now I think this shouldn't be a concern. Also, Language could be
confused with the i18n languages and felt like the current name was
suiteable too.

Design of the Project#Show page is done with help from @dimitrieh. This
change is not visible to the end user unless detections are done.

Why and how to enable this is covered in the docs being changed
here. This requires gitlab-org/gitlab-shell@2e8b670 ("Add support for
SSH certificate authentication", 2018-06-14) which has been merged in
and tagged as 8.0.0, so GITLAB_SHELL_VERSION needs to be bumped.

Merging this closes gitlab-org/gitlab-ce#34572 see
gitlab-org/gitlab-shell!207 for the gitlab-shell MR.

Implementation notes:

 - The APIs being changed here are all internal, and their sole
   consumer is gitlab-shell.

 - Most of the changed code is a MR to gitlab-shell, see the
   gitlab-org/gitlab-shell!207 MR. That change covers why only some of
   the internal methods get a new "username" parameter, and why some
   others only get a "user_id".

This reverts merge request !20801

git-lfs 2.5.0 now sets the Content-Type header instead of hard-coding it to
application/octet-stream: https://github.com/git-lfs/git-lfs/pull/3137

To avoid this issue, we explicitly tell the client to use
application/octet-stream.

Closes #49752

While reviewing this branch it was noted that this task was broken.
Given the limited value this task brings, and given the fact that much
of the old behaviour has been moved to be automatically fixed, removing
was a good option.

Suggestion in:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20806#note_91261001

These tasks are happening through housekeeping right now, by default
ever 10th push. This removes the need for these tasks.

Side note, this removes one of my first contributions to GitLab, as back
than I introduced these tasks through: 54e6c004

Closes https://gitlab.com/gitlab-org/gitaly/issues/768

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

The `ORDER BY created_at DESC` clause causes a sequential scan because
there is no index on the `created_at` column. We can sort by `id`
or by `updated_at` to make things fast.

Closes #49767

Workhorse was not able to parse the `headers` property since it was expecting a
key => array as a structure.

Error from workhorse: preAuthorizeHandler: decode authorization response: json:
cannot unmarshal string into Go struct field TerminalSettings.Header of type
[]string

Workhorse was not changed since this api is already used for the environment
terminals.

gitlab-org/gitlab-ce#25990

Since the frontend for this feature isn't ready, better to hide the
confusing field behind a feature flag.

The status is shown for
- The author of a commit when viewing a commit
- Notes on a commit (regular/diff)
- The user that triggered a pipeline when viewing a pipeline
- The author of a merge request when viewing a merge request
- The author of notes on a merge request (regular/diff)
- The author of an issue when viewing an issue
- The author of notes on an issue
- The author of a snippet when viewing a snippet
- The author of notes on a snippet
- A user's profile page
- The list of members of a group/user

Closes #26512

This is in preparation for modifying importers to assign e-mails for
only confirmed emails.

The previous implementation would hit the database each time
and provide a dummy response. If the database goes down, this
means all application workers would be taken out of service.
Simplify this check by using a Rails middleware that intercepts
this endpoint and returns a 200 response.