unlink some destroy listeners

Recently wlroots was updated to assert that signals do not have listeners
attached on destroy.

This is just a preliminar work to fix dwl. At the moment dwl will trigger the
assertions at exit.

References: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4918

do not call waitid(2) in the signal handler when Xwayland is enabled

waitid(2) is not a async-signal-safe function acording to signal-safety(7)

We can stop doing this because wlroots!4926 allows compositors to install
signal handlers for SIGCHLD.

References: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4926

use wlr_xwayland_surface_has_window_type() (wlroots!4553)

References: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4553

manually call updatemons in powermgrsetmode()

Fixes: https://codeberg.org/dwl/dwl/issues/713

specify version for presentation-time (wlroots!4858)

References: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4858

check if the backend supports explicit sync before creating the object (wlroots!4848)

References: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4848

fix a use after free

This line makes dwl crash after closing mpv with the switchtotag patch.

remove unused link member from KeyboardGroup

unnecessary since grouping Keyboard wl_list to use wlr_keyboard_group in 023efce

ΔSLOC: -1

disable scene node unless it is unmanaged

send a configure to unmanaged clients when mapping

configure xdg_toplevels after configuring it's decoration

remove a space before parenthesis in function calls

destroy popups when we can't get it's parent or they don't have monitor

remove a redundant check

resize() now does the same check

avoid using a else block

introduce client_set_scale()

remove unnecessary LayerShell.geom

We only used geom.x and geom.y. We can access those variables directly from the
scene node.

update comment about first fields of Client and LayerSurface order

fix style in configurex11()

fix crash when a client is created while all outputs are disabled