allow creation of failover lagg from netcli

Originally, it was allowed to create lagg interface on TrueNAS HA systems with "failover" type. Creating a "failover" type lagg on TrueNAS HA systems was removed because if that interface is marked critical for failover, it can cause some failover timing issues.

However, we have a customer that sets up their mgmt nics in a failover lagg type and doesn't mark it critical for failover. This is how they setup all their old TrueNAS HA systems but since purchasing a new system and trying to set it up the same, it's now prevented.

This ticket is to do the following:
1. allow failover type lagg creation ONLY in netcli
2. prevent "failover" type lagg interfaces from being marked critical for failover