AKS clusters using Azure CNI should use Azure CNI Overlay

# Rule request

## Suggested rule change

AKS clusters using Azure CNI should use Azure CNI Overlay networking which currently is in **preview**. Azure CNI Overlay currently has some limitations that must be taken in consideration.

With Azure CNI Overlay, the cluster nodes are deployed into an Azure Virtual Network subnet, whereas pods are assigned IP addresses from a private CIDR logically different from the VNet hosting the nodes. Pod and node traffic within the cluster use an overlay network, and Network Address Translation (via the node's IP address) is used to reach resources outside the cluster. This solution saves a significant amount of VNet IP addresses and enables you to seamlessly scale your cluster to very large sizes. An added advantage is that the private CIDR can be reused in different AKS clusters, truly extending the IP space available for containerized applications in AKS.

## Applies to the following

The rule applies to the following:

- Resource type: **[Microsoft.ContainerService/managedClusters]**

## Additional context

[Azure CNI Overlay preview](https://azure.microsoft.com/en-us/updates/public-preview-azure-cni-overlay-mode-in-azure-kubernetes-service/)
[Azure CNI Overlay](https://learn.microsoft.com/en-us/azure/aks/azure-cni-overlay)
[Template reference](https://learn.microsoft.com/en-us/azure/templates/microsoft.containerservice/managedclusters)