hook: Add concurrency tracker to track concurrency of pack object
In order to gather some data for how pack object processes are run concurrently, log each time we fire one off and include the already running total for the given user_id and repository.
This way, we can gain insight into the traffic patterns per user_id and repository. This will also give us insight into which users and which repositories cause pack objects to be the most busy.
Changelog: added
Edited by John Cai