display: Correct check for grab_window_buttons

When we're a Wayland compositor, we get all the events, no exceptions,
so we don't need to grab.

This was masking focusing and raising issues under nested that showed
up under native.
events: Don't check if we have the grab to raise / focus a window

It isn't necessary. As an X11 compositor, we'll only see the event
if we have the grab on the window, anyway.

This was causing issues moving windows as a Wayland compositor.