Add torch support
I know that upowerd is not HAL but since it handled keyboard backlight i figured it might also be worth adding support for torch LEDs (as e.g. found on the Librem5). If this not a good fit i can fold this into a separate daemon.
This is modeled like KbdBacklight and i picked a very similar api (basically only adding
MaxBrightness properties on top). If that works i can look into unifying the code between
Torch but wanted to get some feedback first if that is a possibility at all?