Geo: Rake task to manually sync N projects

Some large, active repos are failing to sync. If the Git 2.16 upgrade does not prevent all of these cases, we may need to manually transfer these repos to the secondary during the GCP migration, after blocking the primary and before the failover.

This rake task would need to:

• Ensure any syncing activity does not conflict with what we are about to do
• Copy the repo(s)
• Ensure that this process cannot be affected by whatever prevents our normal syncing process from completing