Add v4 sub-folder so this module could run with AzureRM provider both v3 and v4.

[lonegunmanb]

Describe your changes

This pr added v4 sub-folder and referenced all .tf files via symbolic link, and patch resources by adding Terraform override files, so the users who'd like to use AzureRM v4 could do it by setting module's source to Azure/aks/azurerm//v4.

Issue number

#000

Checklist before requesting a review

• The pr title can be used to describe what this pr did in CHANGELOG.md file
• I have executed pre-commit on my machine
• I have passed pr-check on my machine

Thanks for your cooperation!