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

iOS/FlipperKitTestUtils/FlipperConnectionMock.m

@@ -9,8 +9,7 @@
 
 @implementation FlipperConnectionMock
 
-- (instancetype)init
-{
+- (instancetype)init {
   if (self = [super init]) {
     _connected = YES;
     _receivers = @{};
@@ -19,29 +18,31 @@
   return self;
 }
 
-
-- (void)send:(NSString *)method withParams:(NSDictionary *)params
-{
+- (void)send:(NSString*)method withParams:(NSDictionary*)params {
   if (_connected) {
-    NSMutableDictionary *newSent = [NSMutableDictionary new];
+    NSMutableDictionary* newSent = [NSMutableDictionary new];
     [newSent addEntriesFromDictionary:_sent];
     if (newSent[method]) {
       newSent[method] = [_sent[method] arrayByAddingObject:params];
     } else {
-      newSent[method] = @[params];
+      newSent[method] = @[ params ];
     }
     _sent = newSent;
   }
 }
 
-- (void)receive:(NSString *)method withBlock:(SonarReceiver)receiver
-{
+- (void)receive:(NSString*)method withBlock:(SonarReceiver)receiver {
   if (_connected) {
-    NSMutableDictionary *newReceivers = [NSMutableDictionary new];
+    NSMutableDictionary* newReceivers = [NSMutableDictionary new];
     [newReceivers addEntriesFromDictionary:_receivers];
     newReceivers[method] = receiver;
     _receivers = newReceivers;
   }
 }
 
+- (void)errorWithMessage:(NSString*)message stackTrace:(NSString*)stacktrace {
+  // Empty Implementation
+  // TODO: Test this method too.
+}
+
 @end