Add the option to run a single Fourslash test.
Add the option to run a single Fourslash test.

mbrowne/typescript-dci,mbebenita/shumway.ts,hippich/typescript,fdecampredon/jsx-typescript-old-version,mbrowne/typescript-dci,rbirkby/typescript,popravich/typescript,mbrowne/typescript-dci,tarruda/typescript,vcsjones/typescript,guidobouman/typescript,popravich/typescript,hippich/typescript,hippich/typescript,mbebenita/shumway.ts,mbebenita/shumway.ts,tarruda/typescript,tarruda/typescript,popravich/typescript,rbirkby/typescript,fdecampredon/jsx-typescript-old-version,fdecampredon/jsx-typescript-old-version,guidobouman/typescript,guidobouman/typescript,rbirkby/typescript,mbrowne/typescript-dci