Android: Close websocket properly when remote server initiates close (#22248)

Summary:
When the remote server closes the websocket, the app doesn't get a 'close' event in Android, There is no issue on iOS.
Pull Request resolved: https://github.com/facebook/react-native/pull/22248

Differential Revision: D13047556

Pulled By: hramos

fbshipit-source-id: c5c56ea8418cfdf734fb51f863b3066856de6512

ReactAndroid/src/main/java/com/facebook/react/modules/websocket/WebSocketModule.java

@@ -147,6 +147,11 @@ public final class WebSocketModule extends ReactContextBaseJavaModule {
             sendEvent("websocketOpen", params);
           }
 
+          @Override
+          public void onClosing(WebSocket websocket, int code, String reason) {
+            websocket.close(code, reason);
+          }
+
           @Override
           public void onClosed(WebSocket webSocket, int code, String reason) {
             WritableMap params = Arguments.createMap();