Add a `force_trigger` method to the jig driver

[clint-lawrence]

This is a potential debugging aid. The idea is a force the jig driver to refresh the hardware signals.

For example, with many of our jigs, if you cycle power to the jig to reset something, all the switching circuits would get reset. Assuming the scripts is running under a debugger, then method would provide an easy was to reset the state off the jig.

You could do this in a slightly hacky way at the moment...

on = jig.active_pins()
off = jig.virtual_map._all_pins
jig.debug_set_pins(off=off)
jig.debug_set_pins(on=on)