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

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

tell xwayland clients they're maximized

like we do to xdg clients when tiled state is not supported.

fix a use after free

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

reorder config.mk variables

By placing the default WLR_INCS and WLR_LIBS before the ones for an
alternative wlroots, they don't need to be commented to enable the
alternative ones.

fix style for client_set_scale()

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

state that the Discord server is community-maintained

Previously I regularly checked the server but it has been quite a long time
since I was able to do it.

Update CHANGELOG.md