introduce an intermediate form; this is going to be used to generate a few different things:
- an interator interface for paginated APIs; the IR will let us re-use
the typify types
- a CLI generator that will generate calls into the generated client
- an automated test harness that will validate the generated client
against a mock server
- add the start of a client support crate
- add support for pre/post request hooks with consumer-specific data
- suggest type names for parameter and response types in case those
types are unnamed
- handle more reference types by resolving them properly
- improve optional parameter generation