* Add `ServiceTypeReferenceInfo` to IR so that generators can recognize what types are referenced from exactly one service (amckinney).
yaml
ServiceTypeReferenceInfo:
properties:
typesReferencedOnlyByService:
docs: "Types referenced by exactly one service."
type: map<commons.ServiceId, list<commons.TypeId>>
sharedTypes:
docs: "Types referenced by either zero or multiple services."
type: list<commons.TypeId>