deposit_read: Simplify api to return only relevant deposit information
With this, the deposit information needed for the deposit loader to build the revision are sent in the "deposit" key. It contains the following keys:
- id: Deposit id
- collection: collection name
- client: client name
- author_date: creation date
- author: author
- committer_date: publisher date
- committer: publisher
This avoids:
- unnecessary redundancy. Metadata were set in multiple places even though identical.
- some information were no longer used (branch name, synthetic, revision type, etc...)
Test Plan
tox
Migrated from D3047 (view on Phabricator)