Add new overload for sending using builder that gives the id back

Author: aurimasc

com.unity.mobile.notifications/Runtime/Android/AndroidNotificationCenter.cs

@@ -716,6 +716,18 @@ public static void SendNotification(AndroidJavaObject notificationBuilder)
                 s_Jni.NotificationManager.ScheduleNotification(notificationBuilder);
         }
 
+        /// <summary>
+        /// Schedule a notification created using the provided Notification.Builder object.
+        /// Notification builder should be created by calling CreateNotificationBuilder.
+        /// Stores the notification id to the second argument
+        /// </summary>
+        public static void SendNotification(AndroidJavaObject notificationBuilder, out int id)
+        {
+            id = -1;
+            if (Initialize())
+                id = s_Jni.NotificationManager.ScheduleNotification(notificationBuilder);
+        }
+
         /// <summary>
         /// Update an already scheduled notification.
         /// If a notification with the specified id was already scheduled it will be overridden with the information from the passed notification struct.