Scarlett Johansson, star of “Black Widow,” is suing Disney over the release of the Marvel film. Johansson says Disney’s failure to give the movie an exclusive theatrical release was a breach of contract that cost her $50 million in box office bonuses. “Black Widow” opened in theaters and was available to stream on Disney+ for a $30 charge on the same day. Johansson’s lawsuit is likely just the beginning of a long battle between stars and movie studios over theatrical compensation in the streaming age.