David Fincher’s “Mank” will not be a movie with very much mass appeal. It will, however, adhere to the tastes of the producers in the Academy voting body who’ve always had a nostalgic yearning for the Golden-Age milieu depicted in Fincher’s film. This is a very dry, dialogue-driven ode to a bygone era of industry guys wheeling and dealing behind the scenes. Shot in black and white, and semi-inspired by the making of “Citizen Kane,” “Mank” chronicles a forgotten era of Hollywood lore, all seen through the eyes of its misunderstood screenwriter, Herman J. Mankiewicz.