CHICAGO — On the third night of Harry Styles’ six-night residency in Chicago, as the British pop star, promising actor and spiritual scion of Mick Jagger took the stage, the United Center rattled, buzzed, seemed to implode in a white-hot screech of 23,000 screams. Every generation or so this happens. Rod Stewart. New Kids on the Block. Marvin Gaye. Justin Timberlake. Elvis. The Beatles. To stand at the center of it is shocking. Even teenagers who plan to live forever hold their ears at the volume. If you’re old enough to remember the sound of the audience on “Cheap Trick Live at the Budokan,” …