Games Team policy on dh_installtmpfiles

Hi,

I have used dh_installtmpfiles many years ago, I think that back then at one
point it was a systemd-only thing so it was appropriate for a Debian derivative
but not for Debian proper when we still want to support alternative
init systems.

This restriction has been lifted some times ago and dh_installtmpfiles[0]
is part of the default debhelper-compat 13 sequence.

My proposal:
   we should strive to review these postinst scripts - some of which
   are 25 years old - and redo those in tmpfiles syntax.

This makes the remaining postinst script smaller and easier to maintain.
this could also bring more cohesions to the access rights under /var/games

In the future with upcoming debhelper-compat 14;
these tmpfiles could also be used to handle the purge phase.

Debian Code Search[1] can help identify such games.

Greetings

Alexandre

[0] https://manpages.debian.org/testing/debhelper/dh_installtmpfiles.1.en.html
[1] https://codesearch.debian.net/search?q=var%2Fgames+path%3Apostinst&literal=1