(python-config-type-instance-20) Make OutputMaterializationConfig and InputHydrationConfig subclasses vanilla objects
These were also using a dynamic class pattern, and for no good reason as far as I can tell. Just make them act like normal objects.
Depends on D1597
Test Plan: BK
Reviewers: max, alangenfeld
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D1599