Ghostwriting — what a thankless task: After countless hours of subsuming the self in another’s life story and personality, you get hardly any credit, not even a byline. But for Kif Kehlmann, the narrator of “First Person,” Richard Flanagan’s seventh novel, it’s a quick route to some cash. With an ancient car, falling-apart sneakers, and twins on the way, Kif is desperate, and a publisher’s offer of $10,000 to ghostwrite the autobiography of conman Siegfried Heidl comes just in time.