[Mobile App Feature]: Add app capabilities "push notifications", "background fetch" and "remote notifications" to fix "ITMS-90078: Missing Push Notification Entitlement"

[KarinBerg]

I only did the following steps to enable iOS push notifications and fix the issue "ITMS-90078: Missing Push Notification Entitlement" mentioned on Slack.

**Enable app capabilities in Xcode**
Before your application can start to receive messages, you must enable push notifications and background modes in your Xcode project.
- Open your Xcode project workspace (ios/Runner.xcworkspace).
- Enable push notifications: https://help.apple.com/xcode/mac/current/#/devdfd3d04a1.
- Enable the Background fetch and the Remote notifications https://developer.apple.com/documentation/xcode/configuring-background-execution-modes.

see Firebase Messaging setup guide: https://firebase.google.com/docs/cloud-messaging/flutter/client#enable_app_capabilities_in_xcode