Feature Request: Add out-of-the-box support for websockets

For anyone that comes looking for websocket support, you can dive in to the built in websocket support for now.

https://gitter.im/luckyframework/Lobby?at=5b5a51a61be9bb57bcc749bd

However, this is obviously something we should support out of the box with Lucky. I've never actually used websockets, so I don't know if they use HTTP methods or not, but looking at Kemal docs I would assume something like

class SomeAction < WebsocketAction
  route "/" do
    # maybe context.on_message
    # or have access to socket.on_message here?
  end
end

Start with Crystal's built-in HTTP::WebSocket support and the linked Kemal websocket documentation. The issue suggests a WebsocketAction with routing, but does not define the API, affected files, tests, or acceptance criteria; completion would require agreeing on that integration and verifying it with websocket behavior tests.