Martin McDonagh’s wickedly clever and unexpectedly touching “The Banshees of Inisherin” begins with a sudden death — of a friendship. Padraic (Colin Farrell) and Colm (Brendan Gleeson), longtime neighbors on a small island off the coast of Ireland, have been friends for many years, until one day suddenly they aren’t. “I just don’t like you no more,” says a stony Colm, by way of explaining why he’s abruptly begun to avoid Padraic on trips to the island’s only pub. Padraic’s face crumples upon hearing it, like a slip of paper about to be thrown away. “You liked me yesterday,” he says, mystified….