x11/nwg-look: add new port

Nwg-look is a GTK3 settings editor, designed to work properly in
wlroots-based Wayland environment. The look and feel is strongly
influenced by LXAppearance, but nwg-look is intended to free the user
from a few inconveniences:

• It works natively on Wayland. You no longer need Xwayland, nor strange env variables for it to run.
• It applies gsettings directly, with no need to use workarounds. You don't need to set gsettings in the sway config file. You don't need the "import-gsettings" script.

WWW: https://github.com/nwg-piotr/nwg-look
(cherry picked from commit c230cc46a6782729bc949eef06a55a75e23beae7)
(cherry picked from commit 499d25767f358208778294c47fd776837b6b1577)
(cherry picked from commit 3226c1d4d5000965740d215e69edfacdff6445c7)