Glen Powell displays killer charm in “Hit Man,” a snappy comic thriller that’s part neo-noir rom-com, part philosophical gut check. Powell, the ace supporting player from “Top Gun: Maverick” who elevated himself to leading man status with winter’s surprise hit “Anyone But You,” plays Gary Johnson, a meek, divorced New Orleans college professor who lives alone with his two cats and drives a perfectly sensible Honda Civic. He does part-time undercover work with the New Orleans police department, helping out as a tech consultant on sting operations, but he gets thrown into the field when he’s ask…