async changeLang(lang) {
            let message = (await langModules["../lang/" + lang + ".json"]()).default;
            this.$i18n.setLocaleMessage(lang, message);
            this.$i18n.locale = lang;
            localStorage.locale = lang;
            setPageLocale();
        }
Change the application language
@param {string} lang Language code to switch to
@returns {Promise<void>}