indirection: made packageName accessible using the binding class

made packageName accessible to receive.dart file and test files via
(await ZulipBinding.instance.packageInfo)?.packageName ?? "com.zulip.flutter"

Author: Abhisheksainii

lib/notifications/receive.dart

@@ -149,8 +149,8 @@ class NotificationService {
         await addFcmToken(connection, token: token);
 
       case TargetPlatform.iOS:
-        const appBundleId = 'com.zulip.flutter'; // TODO(#407) find actual value live
-        await addApnsToken(connection, token: token, appid: appBundleId);
+         // TODO(#407) find actual value live
+        await addApnsToken(connection, token: token, appid: (await ZulipBinding.instance.packageInfo)?.packageName ?? "com.zulip.flutter");
 
       case TargetPlatform.linux:
       case TargetPlatform.macOS:

test/api/core_test.dart

@@ -460,7 +460,7 @@ void main() {
       });
     }
 
-    const packageInfo = PackageInfo(version: '0.0.1', buildNumber: '1');
+    const packageInfo = PackageInfo(version: '0.0.1', buildNumber: '1', packageName: 'com.zulip.flutter.test');
 
     const testCases = [
       ('ZulipFlutter/0.0.1+1 (Android 14)',             AndroidDeviceInfo(release: '14', sdkInt: 34),                      ),

test/model/store_test.dart

@@ -1032,7 +1032,7 @@ void main() {
       if (defaultTargetPlatform == TargetPlatform.android) {
         checkLastRequestFcm(token: '012abc');
       } else {
-        checkLastRequestApns(token: '012abc', appid: 'com.zulip.flutter');
+        checkLastRequestApns(token: '012abc', appid:(await testBinding.packageInfo)?.packageName?? 'com.zulip.flutter.test');
       }
 
       if (defaultTargetPlatform == TargetPlatform.android) {
@@ -1071,7 +1071,7 @@ void main() {
       if (defaultTargetPlatform == TargetPlatform.android) {
         checkLastRequestFcm(token: '012abc');
       } else {
-        checkLastRequestApns(token: '012abc', appid: 'com.zulip.flutter');
+        checkLastRequestApns(token: '012abc', appid:(await testBinding.packageInfo)?.packageName?? 'com.zulip.flutter.test');
       }
 
       if (defaultTargetPlatform == TargetPlatform.android) {

test/notifications/receive_test.dart

@@ -30,4 +30,12 @@ void main() {
         .length.equals(1);
     }, variant: const TargetPlatformVariant({TargetPlatform.android, TargetPlatform.iOS}));
   });
+
+  group('tokens', () {
+    test('APNs token registration using correct app bundle ID', () async {
+      await init();
+      check((await testBinding.packageInfo)?.packageName?? 'com.zulip.flutter.test')
+        .equals('com.zulip.flutter.test');
+    }, );
+  });
 }