use `/etc/vconsole.conf` to set XKB settings

Since systemd v253 systemd-localed reads:

XKBLAYOUT=
XKBMODEL=
XKBVARIANT=
XKBOPTIONS=

Which would allow for keymap setup to work OOTB for certain X11 WMs. And is cleaner than forking a localectl

Wayland WMs usually respect XKB_DEFAULT_* env vars similarly, usually through /etc/environment