The xwayland window type XWAYLAND is not handled by the shell at all,
instead libweston-desktop maps such surfaces itself. However, it forgot
to set weston_surface::is_mapped and weston_view::is_mapped.

weston_surface::is_mapped affects the behaviour of weston_view_unmap()
and weston_surface_attach().

weston_view::is_mapped affects the behaviour of weston_view_unmap() and
weston_view_destroy().

When manually mapping a window of type XWAYLAND, mark both the view and
surface as mapped. This follows the expections in libweston, even though
the meaning of is_mapped is not clearly defined for either surface or
view.

Also, when the XWAYLAND window is manually unmapped, unmap the
weston_surface. This updates weston_surface::is_mapped to reflect the
state. However, as a side-effect it will also unmap all sibling views,
should any exist.

v2: rename surface_base to wsurface
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Acked-by: Daniel Stone <daniels@collabora.com>