CMT has announced a star-studded special honoring country star Vince Gill’s music career. The announcement was made Thursday during Gill’s sold-out residency run at Nashville’s Ryman Auditorium. “CMT GIANTS: Vince Gill,” an all-new 90-minute star-studded special celebrating Gill, will premiere at 9 p.m./8 p.m. CT on September 16 on CMT. CMT will feature Brad Paisley,…