Move wheel speed sensor to the motor ESP32 #1

Think it might be better to shift the wheel speed sensor over to the same ESP32 that's already handling the shaft speeds. It'd involve cutting a trace on the PCB and adding a jumper wire.

In the firmware, it'd probably necessitate a shift toward labelling things as "shaft speed", and have arrays 4 units wide. Then have some contants for each sensor index defined in the header.

On second thought - maybe not. I know it'll wind up duplicating code to do the wheel speed sensor on the primary ESP32, but that way the decision and management of manual override periods (and whether the automatic control is enabled or not) is all contained in the primary ESP32, rather than needing to be catered for in the I2C comms between the two.