We need a means to add firewall rules

Please see https://jira.ixsystems.com/browse/NAS-105060 and several forum threads from other True/FreeNAS users seeking this feature.

With TrueNAS becoming more widely used in production environments and and private users wishing to access their personal cloud over the web, sometimes uninvited guests will try to bombard the server with unwanted traffic.

It is becoming essentially to allow for setting the firewall. It wouldn't be so bad if the ipfw command and all settings to persisted after reboot, but it doesn't, so we need a UI to add persistent rules to it now.

The previous ticket was closed as needing more interest, but it has interest from a fair amount of users, and now I'm adding myself to the list.

A feature like this is becoming more and more necessary in our times as cybersecurity becomes more and more of an issue.