West Side Story at a resident theatre? It's enough to make a designer faint. Still, more and more theatres are featuring big musicals because they bring in big audiences and big money. In that case, there's nothing to do but forge ahead and find creative ways to make it happen. Such was the case with set designer Troy Hourie, when he took on the Arthur Laurents — Leonard Bernstein — Stephen Sondheim classic, which was produced by Syracuse Stage for a run last December.