Teach git-repack to write packfiles based on a filter to different object databases
For the goal of space saving, we want the ability to segment out different kinds of Git objects into more than one object database. An example use case is if we wanted to write all blobs greater than 1g to its own object database, while keeping everything else in the main object database.
Teach git-repack(1)
to recognize a new configuration that can be used to specify where to write objects to based on a filter. The alternates mechanism will then be used to connect the repository to alternate object databases.