add property_action?

[hidaris]

In some scenarios, such as switching lights on and off, we need to do something extra to synchronize the state with the device after updating the properties, but webthing-python doesn't seem to implement this feature, I add this in aiowebthing, property:

async def property_action(self, property_):
     """
     Additional action when a property change.
     property_ -- the property that changed
     """
     pass

usage example:

class Z2mThing(Thing):
    async def property_action(self, property_):
        if property_.name == "state":
            value = "ON" if await property_.get_value() else "OFF"
        else:
            value = await property_.get_value()
        await mqtt.publish(f"zigbee2mqtt/{self.id}/set", {property_.name: value})

[mrstegeman]

Couldn't this all be done as part of the value_forwarder callback in the Value class?