FR: support idle-inhibit-unstable-v1

I guess that xfce4-power-manager panel plug-in shall work with idle-inhibit, like waybar-idle-inhibitor

Could you elaborate? I guess power-manager honors idle-inhibit via its idle-notify usage, but what would the plugin be supposed to offer as functionality?

EDIT: Ah, enable inhibit on its own surface perhaps?

Yes, I mean that by plug-in we will can enable idle-inhibit(presentation-mode?) via middle-button click, and this display status of inhibition

Oh yes, it's true that there's the presentation mode, which should already more or less achieve this result, I think. But it could activate idle-inhibit indeed.

added 2. Feature 3. Need Info 5. Panel Plugin/Systray 5. Wayland labels

removed 3. Need Info label

changed milestone to %Xfce 4.22