tablet: add tablet tool pressure range configuration
This sits on top of !963 (merged)
Add a configuration option to reduce the available hardware range to a fraction thereof. This is done by copying the absinfo struct for the pressure value and adjusting that copy's minimum/maximum value for scaling into the target normalized range.
The 1%/5% tip thresholds are kept but pressure offset detection is disabled if there is a custom pressure range.
Unlike the pressure curve which is implemented in the compositor, the pressure min/max range needs to be in libinput, primarily because the tip threshold needs to adjust to any new minimum, allowing for light touches with a pen without triggering tip down even at a higher hardware pressure.
cc @pinglinux, @jigpu especially for the tilt handling that's in this MR
Related to #952