Film Forum is presenting a restored version of Jean-Pierre Melville’s “Army of Shadows” (1969) on the heels of its retrospective dedicated to the revered director. By many lights, this late film is considered Melville’s finest achievement, though it was vilified in France at the time of its release. The picture received sparse distribution outside its native country. Historians peg its poor performance to historical circumstances: Politics, as often happens, got in the way.