Tennessee Williams’s “Ten Blocks on the Camino Real,” opening Thursday at Charlestown Working Theater, is a lyrical fantasy about characters in a Latin American town, including the American boxer Kilroy, the hotel owner Gutman, and the sexy Esmerelda. If that sounds familiar, it’s probably because “Ten Blocks” is an earlier, shorter version of “Camino Real,” the Williams play that flopped on Broadway in 1953.