Several pcbnew_tools utilities read a file from the command line.
Instead of replicating this code, centralise the code in
qa_pcbnew_utils, which allows simpler reuse.
THe utilities are:
* polygon_triangulation
* polygon_generator
* drc_tool
pcb_parser keeps its own function, as that is the focus of the tool,
and its likely to have its own instrumention.
This also adds the ability to read from stdin for the above tools,
which means fuzz testers could theoretically work with them, and it
also can make life easier if you can pipe a board to the executable
directly.