Salt: Update / rework the set of base installed packages

[felixalbrigtsen]

Some packages, such as iptables, rsyslog and rsync should be present on all hosts in salt.
We can easily list all installed packages, and find the set of packages that are universally present on all/most machines.

There are probably also a lot of outdated packages that are no longer required, or that should be replaced with alternatives.

Note: It might be smart to verify package names, and adjust for freebsd, nix and other potentially relevant package managers.