Reorganise for easier extraction

Summary:
To make the DataSource abstraction reusable for other teams and an upcoming talk, this diff moves all DataSource storage & virtualization logic in one folder.

Will set up a build process and demo project in later diffs.

Reviewed By: nikoant

Differential Revision: D28056700

fbshipit-source-id: 7cfe5b40bbbe387da711f765a604a45029d451c7

desktop/flipper-plugin/src/utils/useInUnitTest.tsx

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+/**
+ * Check if we are currently running a unit test.
+ * Use this hook to disable certain functionality that is probably not going to work as expected in the JSDom implementaiton
+ */
+export function useInUnitTest(): boolean {
+  return process.env.NODE_ENV === 'test';
+}