In Gregg Ostrin’s one-act play “Kowalski,” a playwright and an actor meet cute. It’s a summer night in 1947, and Tennessee Williams is at his Provincetown beach house discussing his upcoming project, “A Streetcar Named Desire,” with a friend and colleague, the director Margo Jones. During their chat, he mentions a young, relatively unknown performer who’s set to audition for the male lead, though he has more established names in mind.