public IActionResult ChooseCustomer(Guid customerKey)
{
var cookie = new CheckoutCookie(HttpContext.Request.Cookies, HttpContext.Response.Cookies);
var service = new CheckoutCookieService(cookie.GetValue());
service.AddCustomer(customerKey);
cookie.AddOrUpdateCookie(service.EncodeForCookie());
return(RedirectToAction("Index", "Items"));
}