[firebase_messaging] intent-filter for onResume/onLaunch no longer useful

[woprandi]

The documentation specify to add an <intent-filter> bloc in the AndroidManifest.xml to get onResume and onLaunch called when the user click on the notification in the system tray :

  <intent-filter>
      <action android:name="FLUTTER_NOTIFICATION_CLICK" />
      <category android:name="android.intent.category.DEFAULT" />
  </intent-filter>

But I have these methods called even without add this bloc, I think that should be removed from the documentation if it's no longer useful