"unavailable" Media players should be considered off in Universal player (#14466)

The Universal media player inherits the states of the first child player that is not in some sort of "Off" state (including idle.) It was not considering the "unavailable" state to be off. Now it does.

homeassistant/components/media_player/universal.py

@@ -30,7 +30,8 @@ from homeassistant.const import (
     SERVICE_MEDIA_PLAY, SERVICE_MEDIA_PLAY_PAUSE, SERVICE_MEDIA_PREVIOUS_TRACK,
     SERVICE_MEDIA_SEEK, SERVICE_TURN_OFF, SERVICE_TURN_ON, SERVICE_VOLUME_DOWN,
     SERVICE_VOLUME_MUTE, SERVICE_VOLUME_SET, SERVICE_VOLUME_UP,
-    SERVICE_SHUFFLE_SET, STATE_IDLE, STATE_OFF, STATE_ON, SERVICE_MEDIA_STOP)
+    SERVICE_SHUFFLE_SET, STATE_IDLE, STATE_OFF, STATE_ON, STATE_UNAVAILABLE,
+    SERVICE_MEDIA_STOP)
 from homeassistant.helpers import config_validation as cv
 from homeassistant.helpers.service import async_call_from_config
 
@@ -45,7 +46,7 @@ CONF_SERVICE_DATA = 'service_data'
 ATTR_DATA = 'data'
 CONF_STATE = 'state'
 
-OFF_STATES = [STATE_IDLE, STATE_OFF]
+OFF_STATES = [STATE_IDLE, STATE_OFF, STATE_UNAVAILABLE]
 REQUIREMENTS = []
 _LOGGER = logging.getLogger(__name__)