Joan Jett is so much more than “I Love Rock ’n’ Roll.” It’s true, she became mega-famous from the number-one hit, and that fame intensified with the music video’s endless play on MTV. But that staple of popularity can’t properly define a musician. Jett put her hard work in long before the fame, ripping it up onstage as the backbone of the hard-rock legends The Runaways, influen…