rabbitmq_cluster: federate both amq.topic and zmq.topic

Native AMQP clients publish to amq.topic, but the zmq-to-amqp bridge
publishes to zmq.topic so we can keep track of who's publishing where.

roles/rabbitmq_cluster/tasks/main.yml

@@ -306,7 +306,7 @@
     apply_to: exchanges
     name: pubsub-to-public_pubsub
     state: present
-    pattern: "^amq\\.topic$"
+    pattern: "^(amq|zmq)\\.topic$"
     tags:
       federation-upstream: "pubsub-to-public_pubsub"
     vhost: /public_pubsub