Include depreciated input values in introspection query

[mdnorman]

Currently, the default introspection query ignores any deprecated arguments for query and mutation inputs. Because they are excluded in the introspection query, the server won't even return them as potential values when saving the schema. When a value is deprecated, it should be available along with the deprecation reason since that will typically have instructions about other arguments to use instead so you can slowly migrate your code over to the new values.