[Portland] Adding support for xfce4-sreensaver to xdg-screensaver

[Jarno Suni]

Hi,

I forked xdg-utils and created a branch for the job and also did some
improvement of the script xdg-screensaver.in. My work is ready for
pushing somehow, but I think I have to ask for some help from Xfce
developers concerning some commands regarding the screensaver once
they see my work in GitLab.

GitLab tells me something about Personal Access Tokens that I do not
understand about. At least I could fork and clone with HTTPS. How to
proceed now?