Implement org.freedesktop.Portal.Background for autostart
This allows autostart to work in Flatpaks: https://flatpak.github.io/xdg-desktop-portal/portal-docs.html#gdbus-org.freedesktop.portal.Background
This allows autostart to work in Flatpaks: https://flatpak.github.io/xdg-desktop-portal/portal-docs.html#gdbus-org.freedesktop.portal.Background