`runlevel` not available on newer distro releases

[nsballmann]

On newer distro releases, e.g. Fedora 43+, the runlevel binary is not available anymore (by default).

I think there is a systemd replacement, but I haven't had the time to look into this.

This means though, that lib/facter/runlevel.rb#L9 will produce this unexpected stderr output when running facter or openfact (https://github.com/OpenVoxProject/openfact) on distro releases without a runlevel executable:

sh: line 1: /sbin/runlevel: No such file or directory

One option is to confine fact execution to systems which have the runlevel executable.

Another option is to find the systemd replacement command and obtain the run level that way.

[op-ct]

The simplib runlevel type has a systemd provider that accepts runlevel numbers and converts them into analogous boot targets, so on the fact should probably support that in reverse.