Jem Aswad Senior Music EditorPeter Jackson’s reinterpretation of the film footage that became the Beatles’ swan-song film “Let It Be” has had a long road, even since it was first revealed a couple of years ago — first it was an Apple feature film for 2020, then it became a six-hour docuseries on Disney+ airing this coming Thanksgiving, and that’s on top of the 50-plus years that the footage has been sitting on shelves.