wayland: Implement idle inhibit protocol
The idle inhibitor calls Inhibit and UnInhibit methods of org.freedesktop.Screensaver when the surface is not obscured or when it is obscured respectively.
Tested with mpv /mnt/devel/mpv-build/mpv/build/mpv -v --vo=gpu --no-audio --gpu-context=wayland
Based on: !111 (closed)
Closes: #20 (closed)
Edited by Charbel Assaad