Draft: drop flask-restful

[tehasdf]

This is a draft, and will be changed a lot, and I'll split commits too.

Anyway, the point is, I don't like flask-restful and I want it to go. There's multiple places we use it: [x] the Resource stuff - easily replaced by just flask.MethodView [x] argument parsing - possible to be replaced by pydantic [ ] marshal_with and resource_fields - also possible to be replaced by pydantic