Integrate AutotestSensor example as a LaBox function which can be reached by a menu choice

[mgoyard]

The AutotestSensor example allows you to test LaBox in complete autonomy.
The blinking of the lights and the back and forth movements of loco 3 validate its operation.
Incidentally, in the test I did, pin 12 (PIN_BTN_SEL) remained inactive.
It would be interesting to put this autotest as a function accessible from a HMI menu.
Anyone could customize this function whose script is clear.