wayland: Signal gtk-shell surface destruction to the server

wayland: Signal gtk-shell surface destruction to the server

This adds a "release" destructor for the gtk_surface1 interface which
signals to the server that a surface has been destroyed on the client
side, which the current "destroy" does not do.

Ideally the protocol would have specified a destroy request marked as
destructor to handle this automatically, however this is no longer
possible due to the destroy method being implicitly generated in the
absence of an explicit request in the protocol. Adding a destroy request
marked as destructor now would generate a new destroy method that
unconditionally would send the request to the server, which would break
clients running on servers not supporting that request.