surface: implement wl_surface.offset
References: wayland/wayland!123 (merged)
Breaking change: to check whether the surface offset has changed, WLR_SURFACE_STATE_OFFSET must be used instead of WLR_SURFACE_STATE_BUFFER.
References: wayland/wayland!123 (merged)
Breaking change: to check whether the surface offset has changed, WLR_SURFACE_STATE_OFFSET must be used instead of WLR_SURFACE_STATE_BUFFER.