Breaking into 2 functions - one public, one private, so I can avoid
nested control structures and so on in dealing with errors on the
windows side of things. So, no more namespace, back to a class with
2 static functions, one public one private
If the bios uuid isn't a valid UUID (on mac or windows it 'should be`)
then we read the fallback from the settings and use that, or create and
write one to the settings if it is missing.
