Use this package for deleting service principals: 

https://pkg.go.dev/github.com/Azure/azure-sdk-for-go/services/resources/mgmt/2018-02-01/resources#Client.List

Research what will happen when Graph API is deprecated

The `graphrbac` package used for destroy is deprecated: https://github.com/Azure/azure-sdk-for-go/issues/15769

According to the announcement the Graph API will stop responding to calls. The package suggested as a replacement is still in preview:

"The Microsoft Graph SDK for Go is currently in preview. Use of this SDK in production is not supported." So there is a package available to handle the cleanup but it is in "community preview" mode. To me, this status does not seem like a blocker for the installer use case of destroying service principals.

The installer should attempt a best effort to clean up the service principals. We should determine whether it will be possible/likely to leak service principals and, if so,  document this in the installer output, officials docs or both.

Also depending on how reliable we found the Graph SDK for Go we could build in some sort of redundancy using both the Graph SDK and current method, but I think that is overkill.