Have a single source of truth model for storages

Problem statement

As a Thoth developer, I'm frustrated when I need to delete data and "manually" sync between S3 and SQL.

We should reference Object Storage (S3) inside SQL (alchemy models) and not interact directly with it.

Use something like sqlalchemy-file (#2691 )

N/A

Born from frustation trying to work on #2657
We use S3 as some kind of FS storage (using object names to distinguish classes of objects), see all child Classes of ResultStorageBase) which IMO is an antipattern.

TBD