Make touch capacitance configurable from Micropython

[josuah]

Different people have different body capacitance, so various sensitivity might help compensating different contexts. I.e. "gloves mode".

[vr2045]

Good point. We really need a lot of testing for this. There are only 2-3 parameters the user needs control over in the AZ chip to do this tuning. They will require the AZ registers also to be read so the current value of the prox reading can be printed to the screen for setting the threshold.