Selectors for web-socket messages.

Citrus version: 2.7.4

Hello!
I am trying to understand is it possible to use `selectors` for web-sockets or not. And if it is not is it any way to filter received messages.

I have the following test case. In the same socket the client can send messages and get responses on them and the same time it can get broadcasting messages. Test case contains the following steps:
1. Open socket
2. send message
3. get response for message 2
4. get broadcast message

But I can not predict the behaviour and I can get broadcast message before I get response in step 3. So on step 3 I have error that I expect one message and get the another.
I thought that maybe `selector` functionality can help me here, but seems it does not work with websockets.
I would appreciate any help.

Thank you!

Start by reproducing the four-step WebSocket scenario described in the issue, especially the response and broadcast-message ordering. Then inspect the existing WebSocket receive and selector behavior; done means the response can be distinguished from broadcasts reliably, or the supported filtering limitation is documented.

Written by the indexing model from the issue text.