It may come as a surprise to some that “Ferrari,” Michael Mann’s long-gestating biopic of sports car magnate Enzo Ferrari, is as much a marriage melodrama as it is a thrilling racing picture. But fans who are intimately familiar with the American auteur’s work will recognize that the romantic partnerships in his films have always been as important as the action. Of course, “the action is the juice,” for anyone who has seen Mann’s 1995 magnum opus “Heat,” but the action would be nothing without the stakes offered by the relationships. The wives and girlfriends in Mann’s films are strong, powerf…