By GENE TRAINOR FORT WORTH The city will be home to a new art school next spring.The Art Institute of Fort Worth, a branch of The Art Institute of Dallas, will open April 5 at 7000 Calmont Ave. near Ridgmar mall. The school, which will occupy about 20,000 square feet, will offer bachelors degrees in photography; Web design and interactive media; advertising design; fashion and retail management; graphic design; and interior design.