John R. Lausch Jr. of Kirkland & Ellis LLP was tapped Thursday to serve as Chicago’s top federal prosecutor.President Donald Trump nominated Lausch five months after his administration abruptly ordered 46 U.S. attorneys across the nation to hand in their resignations.Those U.S. attorneys included Zachary T. Fardon, who headed the U.S. Attorney’s Office for the Northern District of Illinois for 3½ years following his selection by President Barack Obama.Lausch must be confirmed by the U.S. Senate …