message: add supportedLocales array into surveyLocalization variable:
diff: currentLocale: "",
  defaultLocale: "en",
  locales: {},
  + supportedLocales: [],
  getString: function (strName: string) {
  var loc = this.currentLocale ? this.locales[this.currentLocale] : this.locales[this.defaultLocale];
  if (!loc || !loc[strName]) loc = this.locales[this.defaultLocale];
  getLocales: function (): Array<string> {
  var res = [];
  res.push("");
  + if(this.supportedLocales && this.supportedLocales.length > 0) {
  + for(var i = 0; i < this.supportedLocales.length; i ++) {
  + res.push(this.supportedLocales[i]);
  + }
  + } else {
  for (var key in this.locales) {
  res.push(key);
  }
  + }
  res.sort();
  return res;
  }
  