Cities and towns shall have all powers set forth in Article 1 (§ 15.2-1100 et seq.) of Chapter 11, known as the uniform charter powers. Such powers do not need to be set out or incorporated by reference in a city or town charter. Counties shall have all powers set forth in Article 1 (§ 15.2-1100 et seq.) of Chapter 11 only when such powers are specifically conferred upon the county.