LibWebSocket+RequestServer: Add a WebSocketImpl using libcurl

This implementation can be better improved in the future by ripping
out a lot of the manual logic in LibWebSocket and rely on libcurl to
parse our message payloads. But for now, this uses the 'raw mode' of
curl websockets in connect-only mode to allow for somewhat seamless
integration into our event loop.

Services/RequestServer/ConnectionFromClient.h

@@ -77,4 +77,6 @@ private:
     NonnullRefPtr<Resolver> m_resolver;
 };
 
+constexpr inline uintptr_t websocket_private_tag = 0x1;
+
 }