engine: util: Add a workaround for printing special resources

This let's our tests compare strings of interface fields!

lang/types/value.go

@@ -232,6 +232,19 @@ func ValueOf(v reflect.Value) (Value, error) {
 			V: f,
 		}, nil
 
+	// TODO: should this return a variant value?
+	// TODO: add this into ConfigurableValueOf like ConfigurableTypeOf ?
+	//case reflect.Interface:
+	//	t, err := TypeOf(value.Type())
+	//	if err != nil {
+	//		return nil, errwrap.Wrapf(err, "can't determine type of %+v", value)
+	//	}
+	//
+	//	return &VariantValue{
+	//		T: NewType(?),
+	//		V: ?,
+	//	}, nil
+
 	default:
 		return nil, fmt.Errorf("unable to represent value of %+v which has kind: %v", v, kind)
 	}