function registerLocaleData(locale, lhlMessages) {
  LOCALE_MESSAGES[locale] = lhlMessages;
}
Populate the i18n string lookup dict with locale data
Used when the host environment selects the locale and serves lighthouse the intended locale file
@see https://docs.google.com/document/d/1jnt3BqKB-4q3AE94UWFA0Gqspx8Sd_jivlB7gQMlmfk/edit
@param {LH.Locale} locale
@param {import('./locales').LhlMessages} lhlMessages