Move init of _contextContainer to init function

Summary:
changelog: [internal]

Move initialisation to `init` function. This allows subclasses of `RCTAppDelegate` to use new architecture when overriding `didFinishLaunchingWithOptions`

Reviewed By: cipolleschi

Differential Revision: D43535602

fbshipit-source-id: 32adb5416e67a63ad168f0ed2480287bf178a6a6

Libraries/AppDelegate/RCTAppDelegate.mm

@@ -33,17 +33,24 @@ static NSString *const kRNConcurrentRoot = @"concurrentRoot";
 
 @implementation RCTAppDelegate
 
+#if RCT_NEW_ARCH_ENABLED
+- (instancetype)init
+{
+  if (self = [super init]) {
+    _contextContainer = std::make_shared<facebook::react::ContextContainer const>();
+    _reactNativeConfig = std::make_shared<facebook::react::EmptyReactNativeConfig const>();
+    _contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
+  }
+  return self;
+}
+#endif
+
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
   BOOL enableTM = NO;
 #if RCT_NEW_ARCH_ENABLED
   enableTM = self.turboModuleEnabled;
-
-  _contextContainer = std::make_shared<facebook::react::ContextContainer const>();
-  _reactNativeConfig = std::make_shared<facebook::react::EmptyReactNativeConfig const>();
-  _contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
 #endif
-
   RCTAppSetupPrepareApp(application, enableTM);
 
   if (!self.bridge) {

packages/rn-tester/RNTester/AppDelegate.mm

@@ -88,16 +88,22 @@ static NSString *const kRNConcurrentRoot = @"concurrentRoot";
 
 @implementation AppDelegate
 
-- (BOOL)application:(__unused UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
+#if RCT_NEW_ARCH_ENABLED
+- (instancetype)init
 {
-  RCTEnableTurboModule(YES);
-
-#ifdef RN_FABRIC_ENABLED
+  if (self = [super init]) {
     _contextContainer = std::make_shared<facebook::react::ContextContainer const>();
     _reactNativeConfig = std::make_shared<facebook::react::EmptyReactNativeConfig const>();
     _contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
+  }
+  return self;
+}
 #endif
 
+- (BOOL)application:(__unused UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
+{
+  RCTEnableTurboModule(YES);
+
   _bridge = [[RCTBridge alloc] initWithDelegate:self launchOptions:launchOptions];
 
   // Appetizer.io params check