Add Hue Startup Brightness

[ryanbrown-at]

I'm very impressed with all the great work being done on the Zigbee2mqtt plugin, but there's one small thing I'm missing:
The option to set the starting brightness after a lamp is physically switched off. I can already set the starting color temperature in Zigbee2mqtt. The Hue app allows setting the starting brightness and temperature, so there should be a way to do this in the Zigbee protocol, right? Or is there a technical reason why it's not possible?