Enable changing the CIDR on shared networks when no IP ranges are defined

[borisstoyanov]

The required feature described as a wish

As an admin I'd love to be able to change the CIDR of a shared network when there's no IP ranges defined. I appeaciate if there are VMs running they can end up on different CIDRs while on the same network, we want to avoid that. So my suggestion is to check if there are IP ranges defined, if no, this basically means there's no VMs on the network, at this stage this should allow the change of the CIDR, thoughts?

[adietrich-ussignal]

While I am very close to the original request, I think it only partially captures the desired behavior. I feel that having the ability to change the CIDR when one already exists is still a valid behavior that should be accounted for in this, given appropriate guardrails. I would think a CIDR change should also be permitted if no instances exist on said network. Accounting for the virtual router, either have the VR stop when this is performed, or require the operator to stop the VR before changing the CIDR on an existing shared network with a CIDR.