add standard Skus_List API support

[cataggar]

Clear and concise description of the problem

It is documented internally at ARM SKU API Contract with Customer.. The Azure VMware Solution already supports the API, but I'm having a bit of trouble putting together the TypeSpec for it in https://github.com/Azure/azure-rest-api-specs-pr/pull/20131 . Like the Operations API, I would prefer not to use a common definition.

Checklist

• Follow our Code of Conduct
• Check that this issue is about the Azure libraries for typespec. For feature request in the typespec language or core libraries file it in the TypeSpec repo
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[cataggar]

You can use az rest to use the API for different resource providers that support it. Here are two examples.

az rest --method get --uri $'/subscriptions/($subscription)/providers/Microsoft.AVS/skus?api-version=2023-03-01'
az rest --method get --uri $'/subscriptions/($subscription)/providers/Microsoft.Compute/skus?api-version=2023-10-02'