Live Streams Component (#21473)

* initial commit of streams

* refactor stream component

* refactor so stream formats are not considered a platform

* initial test and minor refactor

* fix linting

* update requirements

* need av in tests as well

* fix import in class def vs method

* fix travis and docker builds

* address code review comments

* fix logger, add stream start/stop logs, listen to HASS stop

* address additional code review comments

* beef up tests

* fix tests

* fix lint

* add stream_source to onvif camera

* address pr comments

* add keepalive to camera play_stream service

* remove keepalive and move import

* implement registry and have output provider remove itself from stream after idle, set libav log level to error

script/gen_requirements_all.py

@@ -45,6 +45,7 @@ TEST_REQUIREMENTS = (
     'aiohue',
     'aiounifi',
     'apns2',
+    'av',
     'caldav',
     'coinmarketcap',
     'defusedxml',