test(bench): add cases with `fs.stat()` and `fs.statSync` for `bem-walk`
test(bench): add cases with `fs.stat()` and `fs.statSync` for `bem-walk`

The ENB and `scan-level` add `mtime` to file info (used `fs.statSync()`).

To comparison was honest need run `fs.statSync()` for each file.

bem-sdk/bem-walk,bem/bem-walk,bem/bem-naming