There were some impossible calculations made this summer in the making and marketing of Tom Cruise’s seventh mission as Ethan Hunt, the gambit of a gargantuan almost $300m budget yet to prove a decision well-made, the sequel heading for a somewhat destructive financial reckoning. But before the final tally is in, the film’s production company Skydance is hoping for a far easier win with similarly themed thriller Heart of Stone, a potential Netflix franchise-starter, cushioned by lower costs and lower stakes. There’s also, predictably, a lower level of enjoyment to be had here but given the sky-high bar Cruise has set for the Mission: Impossible series, that doesn’t mean that the streamer’s copycat caper is as unrewarding as one might expect. Netflix’s big-boy actioners have mostly felt more mock than blockbuster, from 6 Underground to The Gray Man to Red Notice, pale imitations of films that were already pale imitations of something else in the first place. But Heart of Stone, as disposable and derivative as it might be, is a notable step up, playing …