[Feature] Automatically upgrade an AKS Control Plane Only

[liad5h]

Is your feature request related to a problem? Please describe.
AKS supports only the two most recent patch versions of each of the supported minor versions.
Due to this limitation, it is hard to keep up with AKS patch versions. We end up upgrading our clusters every ~2 months.

We wanted to use AKS auto upgrade to keep the control plane updated and update the worker nodes when we have the time (exactly how we do it in AWS).
As of right now, AKS does not support auto upgrade of only the control plane - https://learn.microsoft.com/en-us/azure/aks/auto-upgrade-cluster?tabs=azure-cli#cluster-auto-upgrade-limitations.

Describe the solution you'd like
We would like to be able to enable auto upgrade only on the control plane.

Describe alternatives you've considered
The alternative is to manually upgrade the control plane every time a new patch version is released.

[microsoft-github-policy-service]

@kaarthis, @sdesai345 would you be able to assist?