“Bosch: Legacy” isn’t so much a spinoff as a continuation of Amazon’s long-running Los Angles noir, which came to an end last year and was simply called “Bosch” for its seven-season run. This time out, with legacy on the mind, our squinty hero Hieronymus Bosch — Harry to all who know him — has handed in his LAPD detective badge and he’s working for himself, out of nondescript office, as a private investigator. If you think that means fewer dead bodies and threats of violence crossing his path, you don’t know Harry. Played with a quietly intense charisma by Titus Welliver, the show has moved fr…