Migrate database to GORM and new schema

[jessegeens]

Following ADR-Reva-003, this PR refactors the sharing SQL logic to now use GORM, an ORM for Go. This change also comes with newly written unit tests for all the database logic.

[diocas]

Some questions and comments. Haven't had the time to review the tests yet.

[diocas]

Another round of comments... Can we also add the annotations that set the indexes and constraints to the gorm models?

[diocas]

Why do we do this in 2 steps instead of doing it in the first switch? It's also because it's making me a bit confused that you can change both state and hidden fileds of a share, but then, the state overwrites the hidden value? Not sure I'm making sense...

[jessegeens]

The switch rs.State should indeed be moved up to case "state" or it will override hidden.

However, I think we have to review some time how we handle the "ShareStates", because now we kind of have double information (we use ShareState_SHARE_STATE_REJECTED to mean hidden, but even the CS3 API ShareState has a field for Hidden, so this seems to be redundant)

[glpatcern]

I remember arguing with the web people at the time about this... the reasoning was that they wanted IIRC:

• accepted (= sync-able) + visible
• accepted + hidden (but still sync-able)
• rejected (and not sync-able)

Now we're adding the sync as well and there's probably too much redundancy. Let's simplify? -> let's have a quick chat?

[diocas]

As discussed via MM, I would also like to confirm that null values (via manually inserted rows) do not break anything. (or, we just set annotations with the proper sql configs).