setLanguage = (req, res, state) => {
  if (req.user && req.user.language) {
    req.setLocale(req.user.language);
  } else if (req.cookies?.lang) {
    req.setLocale(req.cookies?.lang);
  }
  if (req.user) Object.freeze(req.user);
  set_custom_http_headers(res, req, state);
}
Sets language for HTTP Request / HTTP Responce
@param {object} req
@param {object} res
@param {string} state
@returns {void}