Move mqtt from eventbus to dispatcher / add unsub for dispatcher (#6206)

* Move mqtt from eventbus to dispatcher / add unsub for dispatcher

* Fix lint

* Fix test

* Fix lint v2

* fix dispatcher_send

homeassistant/helpers/dispatcher.py

@@ -1,13 +1,24 @@
 """Helpers for hass dispatcher & internal component / platform."""
+import logging
 
 from homeassistant.core import callback
+from homeassistant.util.async import run_callback_threadsafe
 
+
+_LOGGER = logging.getLogger(__name__)
 DATA_DISPATCHER = 'dispatcher'
 
 
 def dispatcher_connect(hass, signal, target):
     """Connect a callable function to a singal."""
-    hass.add_job(async_dispatcher_connect, hass, signal, target)
+    async_unsub = run_callback_threadsafe(
+        hass.loop, async_dispatcher_connect, hass, signal, target).result()
+
+    def remove_dispatcher():
+        """Remove signal listener."""
+        run_callback_threadsafe(hass.loop, async_unsub).result()
+
+    return remove_dispatcher
 
 
 @callback
@@ -24,6 +35,19 @@ def async_dispatcher_connect(hass, signal, target):
 
     hass.data[DATA_DISPATCHER][signal].append(target)
 
+    @callback
+    def async_remove_dispatcher():
+        """Remove signal listener."""
+        try:
+            hass.data[DATA_DISPATCHER][signal].remove(target)
+        except (KeyError, ValueError):
+            # KeyError is key target listener did not exist
+            # ValueError if listener did not exist within signal
+            _LOGGER.warning(
+                "Unable to remove unknown dispatcher %s", target)
+
+    return async_remove_dispatcher
+
 
 def dispatcher_send(hass, signal, *args):
     """Send signal and data."""