Switch VTX power on arm

I have now added the setting to automatically switch the VTX power on arming of the Goblin.

The problem I had was that I have to wait a while for the GPS to connect to the satellites and if the VTX is at full power it gets really really hot and doing that too often will shorten the life of the VTX or lead to it blowing.

I also keep forgetting to set the power higher before launching, have to land and set it and then take off again, all of which wastes battery and my fly time.

Goodbye to that problem.