feat: add support for tagging + SessionCollection

[Julien-R44]

Close #92

Add session tagging support, allowing sessions to be linked to user ids + SessionCollection API

New APIs:

• ctx.session.tag(userId) -> Tag the current session with the given user id
• ctx.session.tagged(userId) -> Get all session IDs for the given user id
• ctx.session.destroySession(sessionId) -> Destroys the given session
• ctx.session.getSession(sessionId) -> Get the given session by its id

And basically, the same methods for SessionCollection

• sessionCollection.tag(sessionId, userId) -> Tag the given session with the given user id
• sessionCollection.tagged(userId) -> Get all session IDs for the given user id
• sessionCollection.destroySession(sessionId) - Destroys the given session
• sessionCollection.getSession(sessionId) -> Get the given session by its id

Tagging is only supported by Redis, database, and memory => If calling those methods with another driver we throw an error
DB implementation is standard, we add a nullable index_id column.
Redis implementation: we uses a SET per user (session_tag:{userId}) to store session ids. One important thing to note is, expired sessions are lazily cleaned up when tagged() is called. Which is not ideal, but tbh I think its fine, probably more than negligible. Another approach could be to also have some sort of gcProbability for it, like we did in #93. But yeah honestly i think its fine like that, lemme know what do you think !

[thetutlage]

Should we have the following methods?

• ctx.session.tagged(userId) -> Get all session IDs for the given user id
• ctx.session.destroySession(sessionId) -> Destroys the given session
• ctx.session.getSession(sessionId) -> Get the given session by its id

The ctx.session is bound to a given session id and it shouldn't really have APIs to act on other session ids, that is what the collection will do.

Also, if I look at it practically, we will only call ctx.session.tag to tag the current session with the logged-in user and never reach for other methods. They will always be accessed via the SessionCollection.

[Julien-R44]

agreed, very right. i actually hesitated to add them and ended up doing it just for consistency. But yeah, its indeed a bit weird to be able to call getSession from ctx.session ..

methods have been removed
Also about "Should we return just the ids or the entire session objects?" => totally fair point. updated that as well !