Refactor MQTT (#24010)

* refactor mqtt so that Frigate owns the transport lifecycle instead of delegating it to paho

* release the shutdown barrier on worker crash and replay retained publishes the broker never acked

* collapse in-flight retained values by topic and release the shutdown barrier from a finally

* replay the outage buffer before the publish queue so newer values are not reverted

frigate/app.py

@@ -335,6 +335,7 @@ class FrigateApp:
             self.ptz_metrics,
             comms,
         )
+        self.dispatcher.start_communicators()
 
     def init_profile_manager(self) -> None:
         self.profile_manager = ProfileManager(