docs: Use message.data instead of message.notification for Firebase Cloud Messaging

[bangseongbeom]

• Use data instead of notification

  Notification does not support url property.

• Use optional chaining operators more precisely

• Replace Linking.removeEventListener

  Linking.removeEventListener is deprecated.

  See: https://reactnative.dev/docs/next/linking#removeeventlistener

• Add @react-native-firebase/messaging imports

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