Add a new QtInstanceNotebook class that is the
weld::Notebook implementation using a native
Qt widget. It uses a QTabWidget.
Initially, all methods trigger an assert;
the actual logic still needs to be implemented
in future commits.
Let QtBuilder handle "GtkNotebook" objects by
creating a QTabWidget and let
QtInstanceBuilder::weld_notebook return
an instance of the new class.
Change-Id: I5a0671a1ba98bea3e0659e4f280706179bfb4d47
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/176322
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
