Add turn off/turn on to Mill integration

It would be great to have the option to turn off and on Mill devices, and not just be able to set the temperature.

I want to turn the heaters off when opening a door, and back on when closing it. Right now you can only set temperature in the app.

Just turning the temperature down and back up will not work because the room is also integrated into another system that controls temperature based on weather, electricity price, and other factors.

Another plus of turning the heaters off and on would be that they go back to the old set temperature without having to store that somewhere.

Pretty sure, like most climate entities you can switch to off