deposit: Explicit deposit type, either 'meta' or 'code' deposit
This should ease deposit listing in whatever forms (backend db read or client consuming deposit listing).
Deposit types stand for:
- meta: metadata-only deposit
- code: content deposit
This commit includes a migration schema script which adds a new column 'type'. The script is also in charge of migration existing data with the right type values..
Related to #3677 (closed) Depends on !348 (closed)
Test Plan
tox
Migrated from D7228 (view on Phabricator)