Implememt `Dir` API

[streamich]

• [ ] Implement Dir-compatible API
  • [ ] Docs
  • [ ] Implementation
• [ ] Cleanup
  • [ ] Remove from Dir class helper functions
    • [ ] wrapAsync
    • [ ] isFunction
    • [ ] promisify
• [ ] Dir interface
  • [ ] .close()
  • [ ] .close(callback)
  • [ ] .closeSync()
  • [ ] .path
  • [x] .read()
  • [x] .read(callback)
  • [x] .readSync()
  • [x] .[Symbol.asyncIterator]()