While British writer-director Martin McDonagh, a seasoned and well-known theater director, showed incredible promise with “In Bruges” and especially 2012’s underseen “Seven Psychopaths,” it’s safe to say that his Oscar-nominated 2017 film “Three Billboards Outside Ebbing Missouri” catapulted him to a mainstream he was not overly familiar with — nor, I bet, that he really wanted to get cozy with.