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.

Enables frozen string for new files in
directories that had been previously
covered in previous MR's.

Partially addresses #47424.

If you enter the following RFC 2822 compliant address:
`John Doe <john@doe.com>`

Gitlab will attempt to send three emails:
1) John
2) Doe
3) john@doe.com

With this change given the following:
`John Doe <johndoe@example.com>`
`Jane Doe <janedoe@example.com>`

Gitlab will send emails to `johndoe@example.com` and `janedoe@example.com`

When the Gitaly call failed, the exception handling failed
because `method` is expected to have a parameter.

Closes #49096

We saw in production that DispatchWorker was running about twice an hour,
which would schedule twice as many jobs as it should.

For some reason, BatchWorker was running 1000 times per hour, possibly
due to Sidekiq RSS kills that caused these jobs to restart.

Adding an ExclusiveLease prevents these jobs from running more
than they should.

Relates to https://gitlab.com/gitlab-com/infrastructure/issues/4526

This reverts merge request !20103

This adds a recurring Sidekiq job that removes up to 50 000 old web hook
logs per hour, if they are older than 90 days. This will prevent the
web_hook_logs table from growing indefinitely.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/46120

There is only 1 `HEALTHY_SHARD_CHECKS` used:
Gitlab::HealthChecks::GitalyCheck

So we can simplify code to get the list of healthy shard names.

The RepositoryCheck::DispatchWorker will start a
RepositoryCheck::BatchWorker for each healthy shard.

Closes gitlab-org/gitlab-ce#48042

It already existed in EE in the Geo namespace. This change brings it
to CE.

Partially addresses #47424.

Various counters would expose either project names, or full project
paths (e.g. "gitlab-org/gitlab-ce"). This commit changes various places
where we use "add_event" so we no longer expose (potentially) private
information.

Closes https://gitlab.com/gitlab-org/gitaly/issues/817

Closes https://gitlab.com/gitlab-org/gitaly/issues/1236

Closes https://gitlab.com/gitlab-org/gitaly/issues/354