Add Integer serialization to JSON converter

Required to make vibration work for scheduled notifications. May need to add other types also. (Double off the top of my head)

android/src/main/java/io/invertase/firebase/messaging/BundleJSONConverter.java

@@ -166,6 +166,8 @@ public class BundleJSONConverter {
             jsonArray.put(objValue);
           } else if (objValue instanceof Bundle) {
             jsonArray.put(convertToJSON((Bundle) objValue));
+          } else if (objValue instanceof Integer) {
+            jsonArray.put(objValue);
           } else {
             throw new IllegalArgumentException("Unsupported type: " + objValue.getClass());
           }