Add common interface types for `Hit`, `Miss`, `Success`, etc

[malandis]

Currently we have no way of expressing whether a generic request was a Success vs Error, Hit vs Miss, etc. Add interface types to express this. We want:

• Success responses to implement ISuccess
• Hit, Miss, and other non-error responses to also implement ISuccess
• Hit responses to implement IHit
• Miss responses to implement IMiss

Add type annotations to control and data responses.

Survey other specialized types to account for this as well. (eg SetIfNotExists stored vs not stored)