[Feature]: AKS create – support no SSH key scenario

### Description of the new feature

We have a customer scenario highlighting a feature parity gap between Azure CLI and Az PowerShell when creating AKS clusters, specifically around SSH key handling.

Azure CLI supports creating AKS clusters without associating an SSH key using: az aks create --no-ssh-key

In contrast, Az PowerShell (New-AzAksCluster) currently:

Requires an SSH public key (default ~/.ssh/id_rsa.pub), or
Forces -GenerateSshKey

There is no PowerShell flag to explicitly opt out of SSH key creation or persistence and they are using powershell based script to create the clusters.

### Proposed implementation details (optional)

_No response_