Function handle_connect_request 

async fn handle_connect_request<R, S>(
    request: Request<Incoming>,
    context: &ProxyContext<R>,
    listener_isolation: (usize, IpAddr),
) -> Result<Response<String>>
where
    R: Runtime,
    S: AsyncRead + AsyncWrite + Send + Sync + Unpin + 'static,

Return an appropriate reply to the given CONNECT request.