fdo#74702 ImplDrawBitmap functionality moved to protected function

OutputDevice::ImplDrawBitmap() has functionality that cannot be used
by printers. I have moved that into a protected function, ScaleBitmap()

Change-Id: Ia1297e259283b8b2f4cf069e3a64a574592a1846
Reviewed-on: https://gerrit.libreoffice.org/8720
Tested-by: Norbert Thiebaud <nthiebaud@gmail.com>
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>