Update WebSocketModule.java

Summary:
Convert to base64 not utf8

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Closes #15046

Differential Revision: D5451398

Pulled By: javache

fbshipit-source-id: b8c6c7b0fb50ca9558e92d3f63a088e343791b7f

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

@@ -159,7 +159,7 @@ public void onMessage(WebSocket webSocket, String text) {
 
       @Override
       public void onMessage(WebSocket webSocket, ByteString bytes) {
-        String text = bytes.utf8();
+        String text = bytes.base64();
         WritableMap params = Arguments.createMap();
         params.putInt("id", id);
         params.putString("data", text);