Refactor Collection superclass

[mattt]

This PR removes abstract methods from base collection, leaving each collection to define its own get / create / list methods on its own terms.

The primary benefit to having abstract methods defined was to reuse shared logic for reload, but that method is short and required additional maneuvering to define an id field. The downside of this tight coupling was that resources were required to implement methods that would raise NotImplemented. And their signatures for create methods were inflexible, requiring either a mismatch with the parent class or an elaborate workaround with overloads and unpacked typed dict kwargs.