QtPrinterInfo: Improve QPrinterInfo Testing

QtPrinterInfo: Improve QPrinterInfo Testing

Much of the current QPrinterInfo tests fail due to being dependent on
specific physical or network printers being attached.  This change
removes all printer specific tests and replaces them with generic
tests that will use whatever printers are installed.

Note if no printers are installed then the tests will still pass. A
later change will add virtual printers to test returned results are
correct.

Windows test code is also required and will come later.

This does not yet remove the "insignificant" status from the test,
further improvements and code fixes are still required.

Change-Id: I60802445924edb126aadf78337a8cb6f2f3b3d37
Reviewed-by: John Layt <jlayt@kde.org>