“The Picture of Dorian Gray” stars the actress Sarah Snook, and only Ms. Snook. Calling it a one-woman show, though, hardly does justice to the magic trick of multiplicity she performs, a performance worthy of Oscar Wilde and his strange and seductive tale of innocence lost. It takes nothing away from Ms. Snook’s performance to note that she shares the spotlight with Wilde’s preening prose, so sparkling that it could charge its own admission.