This PR builds on some elements of the current upgrade process,
such as upgrade_boot, upgrade_preinstall, upgrade_postinstall, but
replaces the upgrade_run with graphical_upgrade_run to use graphical
methods to upgrade the system.
This would not be possible without necessary settings, that are
performed by graphical_upgrade_prerequisites.
Works for both Gnome and KDE.
d3a6beda3d