x11: Update focus on the X11 display before the MetaDisplay
The meta_display_update_focus_window() call has indirect dependencies on the X11 focus window, in order to determine the correct focus window on the Wayland side (i.e. may turn out NULL with certain X windows).
In order to have the right x11_display->focus_xwindow there, we should perform first the focus update on the X11 display.
Fixes focusing of Java applications, as those don't seem to go through _NET_ACTIVE_WINDOW.
Closes: #819 (closed)