From Tina Turner’s iconic Flame Dress to Cher’s sequined Bob Mackie creations, Denver’s DIVA exhibition celebrates the performers who transformed fashion and entertainment.Tina Turner onstage performing in the Bob Mackie “Flame Dress, ” 1978. Designed by costume and fashion designer, Bob Mackie.Credit: Charles Knight/Shutterstock/Denver Art MuseumIn 1977, as Tina Turner embarked on a solo career after leaving her abusive marriage and musical par…