GPS through Gadgetbridge

@Gordon do you have an idea when this could be implemented?

Honestly at this point I'd be doing basically what anyone would - which is trawling through the source to find out what that "Keep location uptodate" menu option does.

But when you know how to do it, just implement it in BanglejsDeviceSupport to send a gps event via uartTxJSON in the same way all the other events do...