[RFE] Implement `ssh` command

[blanquicet]

Current situation

kubectl aks doesn't provide a way to ssh into the nodes (VMSS instances) of an AKS cluster.

Ideal future situation

Investigate if how we can implement something like this:

$ kubectl aks shh --node aks-agentpool-12345678-vmss000000
# shell in the node

Of course, the idea solution is to not depend on the Kubernetes control plane but use the Azure SDK to be able to provide this functionality even when the Kubernetes control plane is not working properly, e.g. the API server is down. Note: Check if this kind of functionality is also available for VMSS: https://learn.microsoft.com/en-us/cli/azure/ssh?view=azure-cli-latest#az-ssh-vm

However, if it is not possible, we still have the option of using kubectl-node-shell and provide this functionality only if Kubernetes is working properly.

[blanquicet]

Another option is to use kubectl debug under the hood, but at this point, I'm wondering what is the added value that kubectl aks can add respect to kubectl debug?