Introducing Docker Registry replication

Behind an application setting, which defaults to false, this commit
implements the implied CI/CD config. Which means that in the case we
can't find the `.gitlab-ci.yml` on the commit we want to start a
pipeline for, we fall back to an implied configuration.

For now the Bash template has been copied to
`Auto-Devops.gitlab-ci.yml` so the tests actually work.

Fixes #34777

This adds counters for build artifacts and LFS objects, and moves
the preexisting repository_size and commit_count from the projects
table into a new project_statistics table.

The counters are displayed in the administration area for projects
and groups, and also available through the API for admins (on */all)
and normal users (on */owned)

The statistics are updated through ProjectCacheWorker, which can now
do more granular updates with the new :statistics argument.

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