fix(WebSocketSubject): Closes socket when closing socket observer

[bever1337]

Description:

When the output observer is closed because of de-serialization errors, ensure the WebSocketSubject is reset and the WebSocket is closed.

Related issue (if exists): (#5312)

[bever1337]

I don't believe there's any marble testing to be done since this work is making native features observable. In my experience, there is no equivalent framework like msw for mocking and testing websockets. This is my first contribution to RxJS, and I would appreciate anyone's time ensuring my above statement is accurate. Additionally, are there other changes that need to be made in RxJS to support this? Other tests? Docs? Thank you

[bever1337]

I need to research further, but I think the multiplexer can also create the same state where the websocket subject has errored but the underlying socket remains open. I don't want to conflate issues and the multiplexer code is trickier to change because it has more error paths.

[maknapp]

There is a MockWebSocket in webSocket-spec.ts to write tests with. There seems to be only one test for deserializer errors, and it does not check for ws.close. There are certainly more tests to add in this area.