Yarn workspaces

Summary:
1) moved "sonar/desktop/src" to "sonar/desktop/app/src", so "app" is now a separate package containing the core Flipper app code
2) Configured yarn workspaces with the root in "sonar/desktop": app, static, pkg, doctor, headless-tests. Plugins are not included for now, I plan to do this later.

Reviewed By: jknoxville

Differential Revision: D20535782

fbshipit-source-id: 600b2301960f37c7d72166e0d04eba462bec9fc1

desktop/app/src/reducers/__tests__/pluginManager.node.tsx

@@ -0,0 +1,34 @@
+/**
+ * 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
+ */
+
+import {default as reducer, registerInstalledPlugins} from '../pluginManager';
+
+test('reduce empty registerInstalledPlugins', () => {
+  const result = reducer(undefined, registerInstalledPlugins(new Map()));
+  expect(result).toEqual({installedPlugins: new Map()});
+});
+
+const EXAMPLE_PLUGIN = {
+  name: 'test',
+  version: '0.1',
+  description: 'my test plugin',
+};
+
+test('reduce registerInstalledPlugins, clear again', () => {
+  const result = reducer(
+    undefined,
+    registerInstalledPlugins(new Map([['test', EXAMPLE_PLUGIN]])),
+  );
+  expect(result).toEqual({
+    installedPlugins: new Map([['test', EXAMPLE_PLUGIN]]),
+  });
+
+  const result2 = reducer(result, registerInstalledPlugins(new Map()));
+  expect(result2).toEqual({installedPlugins: new Map()});
+});