[1/n] Add id column on tokens and sessions

[david-crespo]

Closes #8139. Token IDs are used in #8227 and #8231 for token CRUD.

WIP. Everything compiles and existing tests work, but we are not yet testing retrieval by ID and we need to think about authz checks on the datastore functions for retrieving tokens and sessions by token string.

This PR would be a lot shorter if not for the fact that the token column was the primary key on both tables, so adding the id requires a bunch of migration steps to change the primary key. There were also a lot of changes to code and tests around making things ID-centric instead of token-centric.

• SQL migrations for adding id col and changing primary key to that
• Add TypedUuid to session and token DB models
• Update authz_resource! and lookup_resource! calls for new primary key
• Update Session trait methods to use id instead of token
• Update app and datastore session and token methods to use ID instead of token
• Update two distinct but nearly identical FakeSession implementations (one for unit tests, one for integration tests) to a) track sessions in a Vec instead of a HashMap with token keys
• Figure out authz situation in new fetch session/token by token string methods

[david-crespo]

I'm realizing FleetChild will probably have to change.

[hawkw]

Overall, this makes sense to me. I had some minor nitpicks and style suggestions.

[david-crespo]

@hawkw I addressed all your feedback (I think) in f3bd37a

[hawkw]

Lovely, thanks for addressing my suggestions!