Add a new QtInstanceProgressBar class that is
the weld::ProgressBar implementation using a native
Qt widget. The widget used is a QProgressBar.
This will be used e.g. by the print progress
dialog, for which support will be declared
in an upcoming commit.
Change-Id: Ic4b162014cd3a09801096cebd38dbdc923f5dbfa
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/175816
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
