xwm: move set_title and set_pid

xwm: move set_title and set_pid

Move the calls to set_title() and set_pid() out of
weston_wm_window_read_properties() and into the three callers, each
slightly different.

xserver_map_shell_surface(): already calls these functions after
creating the shell surface, so no need to add calls.

weston_wm_handle_map_request(): can be called only on unmapped (in X11)
Windows, so no need to add calls.

weston_wm_window_draw_decoration(): window->shsurf and window->surface
are either both set or both NULL, so the check for window->shsurf is
removed when moving the set_title() and set_pid() calls under a
window->surface check.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>