(#20125) Add archlinux firewall class and unit test
(#20125) Use PATH to find (ip|ip6)tables for (ip|ip6)tables provider
(#20125) Use PATH to find (ip|ip6|eb)tables for chain provider
(#20125) Add persistence support for Archlinux platform

This only works with facter 1.7.0-rc1 and up because os_key isn't
properly defined in facter 1.6.18 on Archlinux (it's set to Linux).
Merge branch '20125'

* 20125:
  (#20125) Add persistence support for Archlinux platform
  (#20125) Use PATH to find (ip|ip6|eb)tables for chain provider
  (#20125) Use PATH to find (ip|ip6)tables for (ip|ip6)tables provider
  (#20125) Add archlinux firewall class and unit test