Co-authored-by: Patrick Bajao <ebajao@gitlab.com>

Contributes to https://gitlab.com/gitlab-org/gitlab-shell/-/issues/762

**Problem**

There is a new endpoint for SSH Push implemented in Workhorse. We
want to use it for Geo Git Push calls.

**Solution**

* Define a boolean parameter `GeoProxyPushSSHDirectToPrimary` hidden
behind the feature flag.
* Make a call to `ssh-receive-pack` endpoint for git push commands.

Changelog: added

Contributes to https://gitlab.com/gitlab-org/gitlab-shell/-/issues/762

**Problem**

There is a new endpoint for SSH Pull implemented in Workhorse. We
want to use it for Geo Git Pull calls.

**Solution**

* Define a boolean parameter `GeoProxyFetchSSHDirectToPrimary` hidden
behind the feature flag.
* Make a call to `ssh-upload-pack` endpoint for git pull commands.

Changelog: added

* Use retryablehttp functions
* Catch the result of the Body.Close calls

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/336618

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/336618

Change the usage of http.Client to retryablehttp.Client to take advantage
of the ability to retry queries and calls.

Ensure each of the function calls set their own headers.

Switch the hard-coded HTTP header string to be a constant given to each
of the Client objects.

Co-authored-by: Ash McKenzie <amckenzie@gitlab.com>

Fix capitalization of variables names
Change "cap" to capability to avoid built-in objects
Account for error responses in locks

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/336618

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/336618