git/stats: Start exposing and logging information on references
This MR moves information about loose and packed references into git/stats
and exposes it via a new ReferencesInfo
structure. Furthermore, we add it to the now-renamed RepositoryInfo
structure so that we include the information in our log messages that get posted in various housekeeping RPCs.
It is the final piece to have all information we use for our optimization strategy available via logs.