title: No vibrate in flutter notifications
body: <p>I am using firebase cloud functions to send a notification to a particular user. This is the payload that I am sending from the functions.</p>
  
  <p><code>var payload = {
      notification: {
          sound: "default",
          color: "#ff3296fa",
          vibrate: "300",
          priority: 'high',
          notificationType: "52",
          title: titleToBeShown,
          body: message['message'],
          icon: 'ic_launcher',
      },
      data: {
          click_action: 'FLUTTER_NOTIFICATION_CLICK',
          channelId: channelID,
          channelName: channelName,
          channelType: channelType
      },
  };</code></p>
  
  <p>I am using firebase_messaging (flutter package: <a href="https://pub.dartlang.org/packages/firebase_messaging" rel="nofollow noreferrer">https://pub.dartlang.org/packages/firebase_messaging</a>) to receive the notifications and I have written the codes for onMessage, onLaunch and onResume methods.</p>
  
  <p>So when I send a message using Admin SDK <code>admin.messaging().sendToDevice(token, payload)</code>, it sends it without vibration and sound. How can I add vibration and sound to it? Right now, it feels like a silent notification then. Which will easily be ignored by the users. Both in android and ios, its the same problem. </p>