Someday, I suspect some arts organization will put on a festival of works by John Patrick Shanley that focuses on his penchant for unlikely couples, which will include his landmark first play “Danny and the Deep Blue Sea,” his Broadway outing “Outside Mullingar” and the Oscar-winning film “Moonstruck.” Now, another play can be added to this repertoire, “Brooklyn Laundry,” currently getting its world premiere at Manhattan Theatre Club at NY City Center Stage 1. But whoever that festival producer turns out to be, they may want to ask Shanley to expand this engaging, 75-minute work to give more background and substance to its main female character.