This will help diagnose the source of excessive I/O from Rugged
calls. To implement this, we need to obtain the full list of arguments
sent to each request method.

This adds `rugged_duration_ms` and `rugged_calls` fields to
`api_json.log` and `production_json.log`. This will make it easier to
identify performance issues caused by excessive I/O.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/64676

Whenever we use the rugged implementation, we are going straight to disk
so we want to bypass the disk access check.

Add a module we use as a singleton to determine whether or not rails is
able to access the disk

Attempting to use the API endpoint
/projects/:id/repository/tree?recursive=true would only return a subset
of the results since the full recursive list wasn't actually being
returned.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/61979

This brings back changes in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20432.

For users using Gitaly on top of NFS, accessing the Git data directly
via Rugged may be faster than going through than Gitaly. This merge
request introduces the feature flag `rugged_list_commits_by_oid` to
activate the Rugged method.

For one customer, we saw that ListCommitsByOid was the second highest
used endpoint that may be causing increased load.

The Rugged implementation was recursively scanning the repository to
create `flat_path` because the post-process step was being called from
with a loop. For large repositories, this was significantly slowing
things down. Break the call to `rugged_populate_flat_path` out of this
loop to make this work efficiently.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/59759

This brings back some of the changes in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20176/diffs.

We discovered another N+1 that hits Gitaly `TreeEntry` via the
`RelativeLinkFilter`:
https://gitlab.com/gitlab-org/gitlab-ce/issues/58657. When a blob is
loaded with many relative links, `TreeEntry` is called for each link to
scan the URI type.

There are multiple paths that hit Gitaly `TreeEntry`, and
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/25706 did not
cover all cases. This commit covers another common use case.

For users using Gitaly on top of NFS, accessing the Git data directly
via Rugged may be faster than going through than Gitaly. This merge
request introduces the feature flag `rugged_commit_tree_entry` to
activate the Rugged method.

This brings back some of the changes in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20099/diffs

For users using Gitaly on top of NFS, accessing the Git data directly
via Rugged is more performant than Gitaly. This merge request introduces
the feature flag `rugged_tree_entry` to activate the Rugged method.

Part of four Rugged changes identified in
https://gitlab.com/gitlab-org/gitlab-ce/issues/57317.

This brings back some of the changes in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20343.

For users using Gitaly on top of NFS, accessing the Git data directly
via Rugged is more performant than Gitaly. This merge request introduces
the feature flag `rugged_tree_entries` to activate the Rugged method.

Part of four Rugged changes identified in
https://gitlab.com/gitlab-org/gitlab-ce/issues/57317.

This brings back some of the changes in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20095.

For users using Gitaly on top of NFS, accessing the Git data directly
via Rugged is more performant than Gitaly. This merge request introduces
the feature flag `rugged_commit_is_ancestor` to activate the Rugged
path.

Part of four Rugged changes identified in
https://gitlab.com/gitlab-org/gitlab-ce/issues/57317.

This brings back some of the changes in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20339.

For users using Gitaly on top of NFS, accessing the Git data directly
via Rugged is more performant than Gitaly. This merge request introduces
the feature flag `rugged_find_commit` to activate Rugged paths.

There are also Rake tasks `gitlab:features:enable_rugged` and
`gitlab:features:disable_rugged` to enable/disable these feature
flags altogether.

Part of four Rugged changes identified in
https://gitlab.com/gitlab-org/gitlab-ce/issues/57317.