Additional data consistency checks

[owendelong]

Description

There are errors that can be made in switch configuration data that don't currently get caught.
This will likely never be perfect, but it can definitely be improved.

Acceptance Criteria

No trunk should contain a VLAN not enumerated in the consolidated VLANs file (the result of parsing vlans + all of its includes).
If a VLAN exists in the consolidated VLANs file, but doesn't appear on Uplink and Downlink ports, a warning should be generated -- ideally requiring acknowledgement and verification from a reviewer prior to merging)
If a VLAN exists in the consolidated VLANs file, but is not present in all of the Uplink and Downlinks for at least one "group", an error should be generated and merging should be blocked.
All of the Uplink and Downlink ports within a given group should be identical, or an error should be generated and merging should be blocked.
All IPv6 addresses in configurations should be within the same /48 or an error should be generated and merging should be blocked.