Added react-native run-ios

Summary:
Works the same way as `react-native run-android`, but targets iOS simulator instead. Under the hood, it uses `xcodebuild` to compile the app and store it in `ios/build` folder, then triggers `instruments` and `simctl` to install and launch the app on simulator.

Since Facebook relies on BUCK to build and run iOS app, we probably won't use `run-ios` internally. That's why I'm putting this as public PR instead of internal diff.

To test this, I hacked global `react-native` script to install react native from my local checkout instead of from npm, cd into the folder and ran `react-native run-ios`.
Closes https://github.com/facebook/react-native/pull/5119

Reviewed By: svcscm

Differential Revision: D2805199

Pulled By: frantic

fb-gh-sync-id: 423a45ba885cb5e48a16ac22095d757d8cca7e37

local-cli/runIOS/__tests__/findXcodeProject-test.js

@@ -0,0 +1,57 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+jest.dontMock('../findXcodeProject');
+
+const findXcodeProject = require('../findXcodeProject');
+
+describe('findXcodeProject', () => {
+  it('should find *.xcodeproj file', () => {
+    expect(findXcodeProject([
+      '.DS_Store',
+      'AwesomeApp',
+      'AwesomeApp.xcodeproj',
+      'AwesomeAppTests',
+      'PodFile',
+      'Podfile.lock',
+      'Pods'
+    ])).toEqual({
+      name: 'AwesomeApp.xcodeproj',
+      isWorkspace: false,
+    });
+  });
+
+  it('should prefer *.xcworkspace', () => {
+    expect(findXcodeProject([
+      '.DS_Store',
+      'AwesomeApp',
+      'AwesomeApp.xcodeproj',
+      'AwesomeApp.xcworkspace',
+      'AwesomeAppTests',
+      'PodFile',
+      'Podfile.lock',
+      'Pods'
+    ])).toEqual({
+      name: 'AwesomeApp.xcworkspace',
+      isWorkspace: true,
+    });
+  });
+
+  it('should return null if nothing found', () => {
+    expect(findXcodeProject([
+      '.DS_Store',
+      'AwesomeApp',
+      'AwesomeAppTests',
+      'PodFile',
+      'Podfile.lock',
+      'Pods'
+    ])).toEqual(null);
+  });
+});