* Add unit test for websocket controller
* Add mock for websocket connection
* Add mock for data provider
* Add mock for data provider factory
* Add mock for websocket connection

The WebSocket Controller interacts with:
1. Data Provider: Supplies data to the controller.
2. WebSocket Connection: Handles communication with the client.

To properly test the controller's logic, we mock these interactions.
Since the controller runs two parallel routines (reader and writer),
the tests also ensure both can shut down cleanly.
A done channel is used in the tests to coordinate this process.

…ntroller