Objective: - Implement an Android and iOS app with Firebase Cloud Messaging (FCM) push notification functionality. The app should be able to receive notifications from the foreground and background. The payload data of the notification should contain the date and time to set an alarm. The app should show a custom notification instead of the FCM default notification, indicating that the alarm has been set for the specified time. The app should also ring the alarm at the specified time, regardless of whether the app is in the foreground or background.