Kubernetes version selection is statically defined

This affect multiple templates. Simplest example is;
[Azure Container Service](https://github.com/Azure/azure-quickstart-templates/tree/master/101-aks)

### Issue Details

The `azuredeploy.json` file in many templates (those using AKS) statically define a parameter called `kubernetesVersion` which represents the set of available AKS versions. This parameter appears to be out of date on many/all templates. We can fix these on a one-off basis such as I have just done with #6844 but this is not sustainable longer term.

A better approach is likely to be the creation of a script which is able to regenerate this using the `az aks get-versions` CLI command to pull the supported versions.

I offer no opinion on the best way to then have that dynamic list generation execute at build/run time :-( Because the raw azuredeploy.jason files are directly referenced from github there will need to be some external process which performs some sort of a build and the commits the updated json files back into github.

Review the AKS template example at 101-aks and the azuredeploy.json files that define kubernetesVersion. Start by examining the az aks get-versions CLI command and determine how version data could be regenerated for templates served directly from GitHub. Done means the affected AKS templates receive an maintainable, repeatable version update process.

Written by the indexing model from the issue text.