* Enable Google Assistant OnOffTrait for climate devices that support them
This commit enables the OnOffTrait for climate devices that have the SUPPORT_ON_OFF feature. I have tested this locally with a Sensibo device which supports ON_OFF and a nest device that does not.
* Update trait.py
* Add tests for onoff_climate
* Add OnOff trait to climate.heatpump
* Add on status to heatpump in google_assistant tests