Enable dev menu in tvOS simulator

Summary:
There was no easy way to pull up the dev menu in the tvOS simulator

Run the UIExplorer demo and press cmd+d to bring up the menu
Closes #13584

Differential Revision: D4916967

Pulled By: javache

fbshipit-source-id: 27f50031f65f35dad46ad5ade7b52c7d350b31a2

React/Modules/RCTDevMenu.m

@@ -108,7 +108,7 @@ - (instancetype)init
                                                object:nil];
     _extraMenuItems = [NSMutableArray new];
 
-#if TARGET_IPHONE_SIMULATOR
+#if TARGET_OS_SIMULATOR
     RCTKeyCommands *commands = [RCTKeyCommands sharedInstance];
     __weak __typeof(self) weakSelf = self;