Enable -Wundef for react-native targets

Summary:
Prevent the class of issues seen in D68797482 by making `#if FOO` where `FOO` is not defined an error.

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D68824244

Author: javache

packages/react-native/ReactCommon/react/renderer/graphics/Transform.h

@@ -8,8 +8,10 @@
 #pragma once
 
 #include <array>
+#include <string>
 #include <vector>
 
+#include <react/renderer/debug/flags.h>
 #include <react/renderer/graphics/Float.h>
 #include <react/renderer/graphics/Point.h>
 #include <react/renderer/graphics/RectangleEdges.h>