We need parent_name and config now because it might be necessary to generate a new inline schema.

This is similar to the _PropertyData class that previously existed just to be a return type for _process_properties. Since they were so close already, and ModelProperty also had all of these properties, I figured it made sense to encapsulate them and have ModelProperty just own an instance of this class. I added accessor methods so that model.required_properties still works as an alias for model.details.required_properties.