core: NewInstanceInfo now produces correct "id" for data resources

We need to mimic the old API here, and we weren't doing that quite right
since the "data" prefix was missing from data resources.

terraform/resource.go

@@ -132,6 +132,9 @@ func NewInstanceInfo(addr addrs.AbsResource) *InstanceInfo {
 	// determine from an InstanceInfo alone whether it is a managed or data
 	// resource that is being referred to.
 	id := fmt.Sprintf("%s.%s", addr.Resource.Type, addr.Resource.Name)
+	if addr.Resource.Mode == addrs.DataResourceMode {
+		id = "data." + id
+	}
 
 	return &InstanceInfo{
 		Id:         id,