Add 2-pin header to cut off laser driver VDD

[cemonds]

As an enhancement for laser safety it should be possible to cut off the supply voltage of the laser driver via a micro switch integrated into the case. The easiest way to do this is to add some pads for a pin header with 2 pins into the trace. If you want to use a micro switch you can cut the trace between the two pads, assemble the pin header and connect the switch.