getDateValue(date, format, useTimezone) {
    if (useTimezone) {
      return dayjsDate(date, this.valueFormat, this.timezone).format(convertFormatToDayjs(format));
    }
    return moment(date).format(convertFormatToDayjs(format));
  }
Return the date value as a string.
@param {string|Date} date - The date object or a date string that is momentjs compatible.
@param {string} format - The DateParser code format.
@param {boolean} [useTimezone] - If the timezone should be used.
@returns {string} - Returns the formatted date string.