From a classic white T-shirt, to high-waisted bootcut jeans, no one styles up a simple wardrobe essential quite like Jennifer Lopez. Even ultra-casual dungarees—which Vogue contributing editor Ellie Pithers aptly describes as “the sartorial equivalent of a hot water bottle”—get the superstar treatment from J.Lo. Spotted hand-in-hand with her fiancé Ben Affleck (second time’s a…