Implement idle-inhibit protocol
Some apps, like mpv, use
idle-inhibit protocol in order to signalize that the screen is in use and shouldn't get blanked/locked (like, when watching a video).
So far we claim to support it as we create an object in
self->idle_inhibit = wlr_idle_inhibit_v1_create(server->wl_display);
...but we never do anything with it again.
It seems like what's needed is listening for
idle_inhibit events and calling
self->idle when necessary.