For the first time since 2016’s “Hacksaw Ridge,” Mel Gibson again dons his director’s hat with the new thriller “Flight Risk,” out in theaters Friday. An enjoyable if standard B movie that takes place almost entirely on a small plane, it stars Mark Wahlberg as a contract killer, Michelle Dockery as a federal marshal, and Topher Grace as an accountant coerced into being a government witness in an upcoming trial against a mob boss.