Copy RenderHost, FlipperLib initialization, device definition to flipper-frontend-core

Reviewed By: passy

Differential Revision: D36129746

fbshipit-source-id: 15e32b9482d7fe3a24567d2e6bc087095b98226e

desktop/flipper-frontend-core/src/fb-stubs/constants.tsx

@@ -0,0 +1,12 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+export default Object.freeze({
+  IS_PUBLIC_BUILD: true,
+});