Implement react-native-flipper on iOS (#795)

Summary:
Implement the react-native-flipper native module on iOS. Uses very similar abstractions as on Android.

## Changelog

[react-native-flipper] Support iOS
Pull Request resolved: https://github.com/facebook/flipper/pull/795

Test Plan:
Tested using the RN TicTacToe example app

{F228406333}

Reviewed By: mweststrate

Differential Revision: D19853017

Pulled By: priteshrnandgaonkar

fbshipit-source-id: d93d35ff984b9ba75f812c4c8e3c82e4d550f0c0

react-native/ReactNativeFlipperExample/ios/ReactNativeFlipperExample/AppDelegate.m

@@ -12,7 +12,6 @@
 #import <React/RCTRootView.h>
 
 #if DEBUG
-#ifdef FB_SONARKIT_ENABLED
 #import <FlipperKit/FlipperClient.h>
 #import <FlipperKitLayoutPlugin/FlipperKitLayoutPlugin.h>
 #import <FlipperKitUserDefaultsPlugin/FKUserDefaultsPlugin.h>
@@ -20,12 +19,13 @@
 #import <SKIOSNetworkPlugin/SKIOSNetworkAdapter.h>
 #import <FlipperKitReactPlugin/FlipperKitReactPlugin.h>
 #endif
-#endif
 
 @implementation AppDelegate
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
+  [AppDelegate initializeFlipper:application];
+  
   RCTBridge *bridge = [[RCTBridge alloc] initWithDelegate:self launchOptions:launchOptions];
   RCTRootView *rootView = [[RCTRootView alloc] initWithBridge:bridge
                                                    moduleName:@"ReactNativeFlipperExample"
@@ -53,7 +53,6 @@
 + (void) initializeFlipper:(UIApplication *)application
 {
 #if DEBUG
-#ifdef FB_SONARKIT_ENABLED
   FlipperClient *client = [FlipperClient sharedClient];
   SKDescriptorMapper *layoutDescriptorMapper = [[SKDescriptorMapper alloc] initWithDefaults];
   [client addPlugin: [[FlipperKitLayoutPlugin alloc] initWithRootNode: application withDescriptorMapper: layoutDescriptorMapper]];
@@ -62,7 +61,6 @@
   [client addPlugin: [[FlipperKitNetworkPlugin alloc] initWithNetworkAdapter:[SKIOSNetworkAdapter new]]];
   [client start];
 #endif
-#endif
 }
 
 @end