Add a setting that treats object_id in DAB RBAC as an integer

[AlanCoding]

Proposal:

Introduce a new setting in the DAB RBAC section that specifies:

Treat the object_id field (local ids for references) as an integer field in the API

Internally, we may continue to use a string type indefinitely for consistency with resource registry and to support uuids. However, many apps have no need to support uuid primary keys. For those, it may cause fewer problems for clients to have the object_id, as presented in the API, to be an integer.

This is fairly straightforward to implement. Although serializers may derive type from the model, this is trivial to override to a nullable integer field in the serializer. I don't desire that test_app use this setting by default, but we should have tests for this.

It is unclear if we should have something similar for resource registry.