Add interface to strip zone from Ipv{4,6}Address to form Ipv{4,6}AddressNoZone

While Ipv4AddressNoZone is equivalent with Ipv4Address without a zone, we do not have a fast way of making such an assertion stick - after the check we still need to go through validation.

Expose utility methods from ietfInetUtil which will do such conversions by stripping the zone and instantiatin IpvXAddressNoZone