protocol: define error codes for role reassignment

On the interfaces where it was missing:
- wl_data_device
- wl_shell
- wl_pointer
add an error code for requests that set a wl_surface role when the
wl_surface already has a different role.

This is needed for compositors to appropriately report wl_surface
role violations.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Jasper St. Pierre <jstpierre@mecheye.net>
Acked-by: Jason Ekstrand <jason.ekstrand@intel.com>