[Future] Help users avoid misconfiguring their bridge network

[zjs]

There are a variety of common mistakes users can make when configuring their bridge network. We should help users avoid these.

We may be able to validate that the selected bridge network is a VXLAN or has a VLAN ID configured.

We may be able to validate a bridge network used by one VCH is not selected for use, in any role, by any other VCH.