title: FirebaseMessagingService is not called on app start
body: <p>I want to use FirebaseMessagingService to handle push notifications from the server. But there is not called <code>onCreate</code> function at the start. I thought that this service is initialized automatically when the app starts. Also, I started to send testing notification from firebase cloud messaging but it didn't work.</p>
  
  <pre><code>    class PushNotificationService: FirebaseMessagingService() {
      private lateinit var app: App
  
      override fun onCreate() {
          super.onCreate()
          App.log("FireBaseMsg: starting service")
          app = application as App
      }
  
      override fun onMessageReceived(msg: RemoteMessage?) {
          super.onMessageReceived(msg)
  
          App.log("FireBaseMsg: onMessageReceived")
          val pNotification = msg?.notification
          if (pNotification != null){
              val title = pNotification.title
              val text = pNotification.body
  
              if (!title.isNullOrEmpty() &amp;&amp; !text.isNullOrEmpty()){
                  val p = PushNotification(app, NOTIFICATION_CHANNEL_ID_PUSH, title = title, text = text)
                  p.fireNotification(NOTIFICATION_ID_PUSH)
              }
          }
      }
  
      override fun onNewToken(token: String) {
          App.log("FireBaseMsg: Received token: $token")
          //REGISTER TOKEN
          app.regPushNotification(token, ::onNewTokenCallback)
      }
  
      private fun onNewTokenCallback(err: ApiCallError?){
          if (err == null){
              app.showToast(app.getString(R.string.notification_push_token_failed))
          }
      }
  }
  </code></pre>
  
  <p>Manifest: </p>
  
  <pre><code>&lt;service
     android:name=".services.PushNotificationService"
     android:enabled="true"
     android:exported="false"&gt;
     &lt;intent-filter&gt;
         &lt;action android:name="com.google.firebase.MESSAGING_EVENT" /&gt;
     &lt;/intent-filter&gt;
  &lt;/service&gt;
  </code></pre>