Port directory enumeration related code to WASI#836

jmschonfeld merged 2 commits intoswiftlang:mainswiftlang/swift-foundation:mainfrom

kateinoigakukun:pr-6852de63bfe058b155044011077d5671301acefckateinoigakukun/swift-foundation:pr-6852de63bfe058b155044011077d5671301acefcCopy head branch name to clipboard