add Is() to counterobject

x/ibc/02-client/manager.go

@@ -123,6 +123,10 @@ func (obj Object) Is(ctx sdk.Context, client Client) bool {
 	return obj.client.Is(ctx, client)
 }
 
+func (obj CounterObject) Is(ctx sdk.Context, client Client) bool {
+	return obj.client.Is(ctx, client)
+}
+
 func (obj Object) Update(ctx sdk.Context, header Header) error {
 	if !obj.exists(ctx) {
 		panic("should not update nonexisting client")