xdg-surface: update scheduled toplevel configure
When a client resizes itself, the toplevel configure event continues to send out the old size. This can lead to weird behavior where the old size is applied again after a client is unfocused. Any easy way to avoid this is to simply update the next scheduled wlr_xdg_toplevel_configure when the compositor receives xdg_surface_handle_set_window_geometry from the client. If we get this, we know that the client has resized itself in some way and should update the toplevel sizes accordingly. That way, the next toplevel configure will have more reliable coordinates for clients and they can behave better.