MQTT climate platform [continuation of #8750] (#9589)

* New climate platform with MQTT

* Use STATE_OFF

* Basic tests for climate.mqtt

* lint

* actualy collect coverage

* First tests and fixes

* Add possibility to receive temperature via MQTT

* Require only either sensor or mqtt topic

* Add mqtt publishing for away mode, hold mode and aux heat.

* Use configurabe on/off payloads

* Add pessimistic mode

* Initialize aux and away with False instead of None

* Remove Sensor

* Use correct scheduling method

* Move all methods to coroutines