Migrate standard sample apps to UIScene lifecycle (#2884)

Fixes https://github.com/flutter/flutter/issues/176957

compass_app/app/ios/Runner/AppDelegate.swift

@@ -1,13 +1,16 @@
 import Flutter
 import UIKit
 
-@UIApplicationMain
-@objc class AppDelegate: FlutterAppDelegate {
+@main
+@objc class AppDelegate: FlutterAppDelegate, FlutterImplicitEngineDelegate {
   override func application(
     _ application: UIApplication,
     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
   ) -> Bool {
-    GeneratedPluginRegistrant.register(with: self)
     return super.application(application, didFinishLaunchingWithOptions: launchOptions)
   }
+
+  func didInitializeImplicitFlutterEngine(_ engineBridge: FlutterImplicitEngineBridge) {
+    GeneratedPluginRegistrant.register(with: engineBridge.pluginRegistry)
+  }
 }

compass_app/app/ios/Runner/Info.plist

@@ -24,6 +24,27 @@
 	<string>$(FLUTTER_BUILD_NUMBER)</string>
 	<key>LSRequiresIPhoneOS</key>
 	<true/>
+	<key>UIApplicationSceneManifest</key>
+	<dict>
+		<key>UIApplicationSupportsMultipleScenes</key>
+		<false/>
+		<key>UISceneConfigurations</key>
+		<dict>
+			<key>UIWindowSceneSessionRoleApplication</key>
+			<array>
+				<dict>
+					<key>UISceneClassName</key>
+					<string>UIWindowScene</string>
+					<key>UISceneConfigurationName</key>
+					<string>flutter</string>
+					<key>UISceneDelegateClassName</key>
+					<string>FlutterSceneDelegate</string>
+					<key>UISceneStoryboardFile</key>
+					<string>Main</string>
+				</dict>
+			</array>
+		</dict>
+	</dict>
 	<key>UILaunchStoryboardName</key>
 	<string>LaunchScreen</string>
 	<key>UIMainStoryboardFile</key>

compass_app/app/pubspec.yaml

@@ -35,7 +35,7 @@ dev_dependencies:
   integration_test:
     sdk: flutter
   build_runner: ^2.4.14
-  freezed: ^3.0.0
+  freezed: '>=3.0.0 <5.0.0'
   json_serializable: ^6.9.0
 
 flutter: