Summary:
Split the infinitepush backups code into a separate module.
The infinitepush extension is responsible for providing scratch pushes, as well
as the server-side implementation for storing scratch bundles.
The infinitepushbackup extension uses this feature to provide automatic backup
support. It is an alternative to the commitcloud extension, and the two will
be mutually exclusive.
Reviewed By: DurhamG
Differential Revision: D8204418
fbshipit-source-id: 9279c426da35d451a5e7b39a72f2c91d364e3fd4
