[FEATURE REQ] KubernetesClustersImpl.listKubernetesVersions(Region.WEST_EUROPE) differs from az aks get-versions --location west-europe

**Describe the bug**
The library function KubernetesClustersImpl.listKubernetesVersions() differs from the results that are given by `az aks get-versions --location west-europe`.

***Exception or Stack Trace***
None

**To Reproduce**
Steps to reproduce the behavior:
Execute function and `az aks get-versions --location west-europe`.

***Code Snippet***
`Azure.authenticate(credentials).withDefaultSubscription().kubernetesClusters().listKubernetesVersions(Region.EUROPE_WEST);`
`az aks get-versions --location west-europe --output table`

**Expected behavior**
I expect that the library is on-par with what the AZ cli gives, *or* that there is way to differentiate the results. In my case, I'm looking for the 'default' version, which the Azure Portal gives me (which is N-1 according to the docs). Using this library, I can't get the default version.

So it would be nice to have a function like: listKubernetesProductionVersions(Region.WEST_EUROPE), and a function like defaultKubernetesProductionVersion(Region.WEST_EUROPE).

**Screenshots**
None.

**Setup (please complete the following information):**
N/A

**Information Checklist**
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- [x] Bug Description Added
- [x] Repro Steps Added
- [x] Setup information Added

KubernetesClustersImpl.listKubernetesVersions から開始し、その結果を `az aks get-versions --location west-europe --output table` と比較します。ライブラリが本番用およびデフォルトの Kubernetes バージョンをどのように公開すべきかを判断し、そのうえで、動作が要求されたバージョンと CLI およびポータルの結果を区別していることを確認します。

索引モデルが issue の本文から書いたものです。