Sergio Gómez authored May 26, 2023 and Marius Vlad committed Jul 27, 2023

Currently, the 'parent_destroy_listener' is being paired with
'destroy_signal'. The signal is emitted from kiosk_shell_surface_destroy(),
which is the appropriate place to emit this general-purpose surface destruction
signal.

However, we need to inform the children of the surface destruction before
finding the focus successor and activating it, that is, before calling
find_focus_successor() and kiosk_shell_surface_activate(), which happen before
kiosk_shell_surface_destroy().
Since there are currently other uses for 'destroy_signal' (e.g. in
kiosk-shell-grab.c), don't mess with it and simply add a new
'parent_destroy_signal', placing its emition where we need it.

Signed-off-by: Sergio Gómez <sergio.g.delreal@gmail.com>