Netflix has spent nearly 20 years disrupting the television business, but its most recent programming innovation — live events such as the boxing clash between Mike Tyson and Jake Paul — has been standard fare for traditional networks since the 1950s.Now the streaming group is adding another old-school format to its line-up: the chat show. At a star-studded presentation in Hollywood last week, it announced that comedian John Mulaney would launch a live weekly variety show called Everybody’s Live...