Add an option to reboot to bootloader

Submitted by Stasiek Michalski

Assigned to Xfce Bug Triage

Link to original bug (#16333)

Description

systemd recently added an option to reboot from session directly to bootloader in this PR https://github.com/systemd/systemd/pull/10495 From the Fedora perspective, there is also GRUB2 integration for rebooting to systemd, presented for example in this PR to gnome-session https://gitlab.gnome.org/GNOME/gnome-session/merge_requests/6

The patch to GRUB2 is being implemented in Tumbleweed now, so it would be great to see at least the systemd option to restart to bootloader, if you aren't comfortable having a grub command run from the code like the gnome-session example. We can carry a patch for it downstream in that case.

Version: Unspecified