feat: PneumaticPressureLoader self-detect when sensors need calibration

[pbeaucage]

The OCB100AZ liquid/gas presence sensors we use to detect if liquid is in the cell (and more/fancier things later) occasionally drift over long periods. They have a builtin calibrate routine that resets the diode drive power such that their photodiode reads mid-range (i.e, 2.5 V).

We currently push this "calibrate" button in the sample server every sample. This is pretty non-ideal if rinsing is marginal, because if you calibrate with liquid in the cell, you lose the ability to detect opaque liquids as the sensor will be at 0V with vapor in the cell.

A proposed solution:

- at the end of a rinseCell command, the loader should run a short sensor measurement and get the mean voltage
- if the mean is more than some value away from 2.5 (initial suggestion ± 0.3 V), but less than ~1 V away which would indicate residual rinse, trigger a calibrateSensor
- log this sensor data to tiled to diagnose loading.