The Post’s “You Haven’t Lived Here If You Haven’t …” feature on Sunday traveled to Adams Morgan to enjoy a jumbo slice at Pizza Mart. By featuring just Pizza Mart, we aren’t sure if the Post crowned the jumbo slices that can be found at 2445 18th St. NW as the best on the block, as there are others. (For atmosphere, we’re partial to Pizza Napoli. There’s nothing like post-last call revelry while chowing down…