[Spike] Investigate how to supply terraform with SubscriptionID and TenantID

When using Managed Identities with terraform-azure-provider, the provider needs

In addition to a properly-configured management identity, Terraform needs to know the subscription ID and tenant ID to identify the full context for the Azure provider. 

However, customers use Managed Identities to avoid having to specify such values. It's possible the terraform provider requires them because it is using the old SDK clients. So we need to investigate:

1) Are the any plans from the tf provider to move to the new SDK and not require SubscriptionID and TenantID?

2) If 1) is not happening any time soon, can we find that information out using the Azure SDK and supply the values to terraform? We want to avoid having the customers specify them in osServicePrincipal.json

Resources:

https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/guides/managed_service_identity