NSG and ASG Support in Connectivity Modules

### Description

By itself, the resulting landing zone is a great start but is not fully formed.

### Describe the solution you'd like

If the pipelines are to be used to deploy future changes, the complete starter module needs to be enhanced to include additional resources. An example would be a VNet in the identity subscription used for Domain Controllers.
Another might be NSG's (with rules) for the Connectivity Subscription.

### Describe any alternatives you've considered

I've started to add in AVM modules for some of these items, however it is one thing to feed some YAML parameters into a module, but quite another to cycle through lists of NSGs, ASGs etc. without hardcoding some items or providing a hacky type solution.
If you have a more mature method, I'd love to see it added into the Accelerator please!

### Additional context

Review the existing connectivity modules and deployment pipelines in the Azure Landing Zones repository, along with the AVM module and YAML-parameter approach mentioned in the issue. Define what support is needed for the identity-subscription VNet and Connectivity-subscription NSGs, ASGs, and rules, then establish how completion will be verified without hardcoded lists or a hacky type solution.

Written by the indexing model from the issue text.