We already expose functions to handle the instantiation
of classes such as RPCServer and RPCTransport but the
same was never done for RPCClient so the API is
inconsistent in its enforcement.
This adds a get_rpc_client function that should be used
instead of instatiating the RPCClient class directly to
be more consistent.
This also allows to handle more logic inside the function
in the future such as if implementations for an async client
is implemented, as investigation in [1] has shown.
[1] https://review.opendev.org/c/openstack/oslo.messaging/+/858936
Change-Id: Ia4d1f0497b9e2728bde02f4ff05fdc175ddffe66
4ead7cb2dc