It is not the movie’s raunchy depiction of puppets prostituting themselves, cursing or blowing their heads off that caused Sesame Workshop, the educational nonprofit that produces “Sesame Street,” to file a lawsuit against the film’s creators, STX Entertainment. It is the use of the tagline “No Sesame. All Street” in its promotions that tarnishes a brand beloved by millions of children for nearly 50 years, the lawsuit claims.