SAN FRANCISCO — Shortly before Steve Jobs’ death in 2011, Apple filled a cramped auditorium in Cupertino, California, for the unveiling of its fifth iPhone. The device’s biggest selling point was a new software feature called Siri, which helped cause a jump in iPhone sales. On Monday, Apple is planning to run that play again. For the first time in more than a decade, the tech giant will unveil a suite of iPhones whose signature feature won’t be an improved camera or an updated design, but new so