Fix "creation" of empty built-in firewall chains

[2fa]

Summary

Fixes the issue when you are trying to create an in-built firewall chain in a table that was not been interacted with before.

Additional Context

Currently if you are trying to create in-built chain in an empty table (nat, for example) puppet will apply manifest without actually doing anything every time you run it. This is because firewall module relyes on iptables-save output that will not contain in-built chain if corresponding table not been interacted with yet.

Checklist

• [x] 🟢 Spec tests.
• [x] 🟢 Acceptance tests.
• [x] Manually verified. (For example puppet apply)