json_rpc: setup.cfg is missing entrypoint for json_rpc's list_opts
json_rpc: setup.cfg is missing entrypoint for json_rpc's list_opts

oslo.config is relying on the list_opts entrypoint to automatically
integrate the json_rpc options.

Story: 2009126
Task: 43038

Change-Id: Id50af71faec84bd778422ed86a3b99797158afdb

openstack/ironic-lib