Jem Aswad Senior Music EditorIt is no small understatement to say that David Bowie was at a creative crossroads in 1970 — one that was baffling, possibly even to himself.He began the year essentially as a folksinger coming off of his elaborate first hit, “Space Oddity,” releasing a fey love song to his wife-to-be, Angela (“The Prettiest Star”) before making a drastic pivot into the cerebral proto-heavy metal of “The Man Who Sold the World” album; then closed it out with an odd, hippie-inflected