New Resource: Use of azuread_application_flexible_federated_identity_credential

In the [AWS](https://github.com/hashicorp/terraform-dynamic-credentials-setup-examples/blob/main/aws/aws.tf#L45) and [GCP](https://github.com/hashicorp/terraform-dynamic-credentials-setup-examples/blob/main/gcp/gcp.tf#L68) the runs phrase are wild-carded.

The Azure example has the same application for plan and apply, as Azure provider only supported fully qualify claims. However, just merged in, the provider will has support for [FIC](https://github.com/hashicorp/terraform-provider-azuread/pull/1788) to allow for wildcard:

```terraform
resource "azuread_application_flexible_federated_identity_credential" "plan_and_apply" {
application_id = azuread_application_registration.tfc_application.id
claims_matching_expression = "claims['sub'] matches 'organization:${var.tfc_organization_name}:project:${var.tfc_project_name}:workspace:${var.tfc_workspace_name}:run_phase:*'"
display_name = "my-tfc-federated-credential"
audience = var.tfc_azure_audience
issuer = "https://app.terraform.io"
}
```