Possible feature: thermostat "Active Temperature Sensor" toggle

[scacner]

Determine if it's possible to add an "active temperature sensor" toggle to the thermostat. This toggle can stay up to date based off the rcs_ keys received from the Nest api and can be set when changing the toggle in HA with the set_active_sensor service.

[scacner]

In addition to creating a toggle, see if it's possible to set a custom entity attribute that is set to the current active sensor. This attribute should also change as the active sensor gets change. Also, the toggle could just be based off this custom attribute.

Another thought: Toggle might make more sense to be drop down selector? When thinking of "toggle", I think of on-off switch, or in this case the possibility to only have two sensors. A Nest system could have more than two total sensors.