Auth service can be initialized:
- [current] by passing instantiated authorizer, authenticator, role manager
- [current] by passing service_config, which then uses class registrator to instantiate authorizer, authenticator, role manager
- This approach is easy to use with sharded services
- [new] by passing factory functors which instantiate authorizer, authenticator, role manager
- This approach is also easy to use with sharded services
Refs SCYLLADB-409
bfff07eacb