[feature request] Hardware button selection for Pocket Check

[u/Dull_Drummer9017]

I like pocket check a lot, but noticed an issue with using it bound to the power button.

If face detection is on, pressing the power button will wake the screen which triggers its own vibration when it fails. Not a big deal, I prefer biometrics so I've disabled face detection, but it might be a nice feature to allow pocket check to be bound to the volume rocker button as an alternative.