test: improve fs error message test

- Reuse error validators for sync and async tests
- Validate properties of the errors

PR-URL: #18277
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: joyeecheung