chore: Migrate from Push Subscriptions to FCM Integration

[stigi]

FCM Integration

In this PR the old push_subscription logic is replaced by the new mobile_push/fcm channel.

To get this to work I had to update the SDK and the example app.
In the SDK I refactored the com.magicbell.sdk.feature.pushsubscription into com.magicbell.sdk.feature.fcmtoken.

In the example I've updated:

• The Android SDK version to 34 to have support for the new notifications permissions
• Added the firebase SDK dependency & added a FirebaseMessagingService which is used to register device tokens and receive firebase messages (aka notifications)
• Added an example implementation of a askNotificationPermission function and updateDeviceToken function

Test Plan

I've registered an app with the com.magicbell.example package in the firebase console and added the resulting google-services.json file to the android project (at example/google-services.json).

I then exported the service account private key and registered it with magicbell by sending a PUT to /integrations/fcm.

Now when the app is launched the token registration can be observed in Proxyman:

When calling the disconnectUser(...) function the token is successfully removed:

While the token is registered a push notifications arrive on the device:

magicbell broadcasts create --action-url "act://ion" --content "Via CLI" --title "Check this Broadcast" --custom-attributes '{custom:"Value"}' --recipients "hi@ullrich.is"

The data of the notification message can be handled in onMessageReceived :

• message.data constains custom values and action URL
  
• message.notification.title and message.notification.body contain title and body