The reason is that there were several batches of
4-port .318-01 based 801-PC systems shipped specifically
as multiseat ones (with two RX570 or three simpler GPUs),
and it's more reasonable to provide out-of-box support
for those in a new release instead of having to resort
to manual setups with alterator-multiseat, messing with
the installer-provided configuration by hand or giving up
(or, well, building a sideline installer images with
custom udev-conf packages).

This should have been done when reworking Workstation,
but better that late than making a copy for Education.

NB: directory name has been chosen to both sort late
    (so that functionality related checkboxes come first
    and graphics setup related ones sit down there), and
    to relate to X11 as well.

Four checkboxes with "Elbrus 801-PC" prefix look a bit too much,
let's put these under a parent one; the counter-argument is that
selecting that parent checkbox is going to provide message telling
that there are conflicts within -- the proper widget would be a
dropbox with the number of seats but we don't do that just yet
in alterator-pkg.

The autologin group goes there too; still a hack that should be
replaced by proper alterator-users multiseat support.

This started as a three-seater 801-PC support for
ALT Education 9.0 for Elbrus.

These describe what's needed to set up a single-seat (as usual,
now just default) or dual-seat (out-of-box, given a checkbox)
Elbrus 801-PC.

Huge thanks to bircoph@ for actually implementing this!