fix: path relative and join method

[SyMind]

Summary

1. In JavaScript path.join('/a', '/b') == '/a/b', it is different behavior between Rust.
2. Use sugar_path for calculate relative path.

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

[netlify]

✅ Deploy Preview for rspack canceled.

Name	Link
🔨 Latest commit	9b64851
🔍 Latest deploy log	https://app.netlify.com/sites/rspack/deploys/67738ff29e55540008e0f5e1

[codspeed-hq]

CodSpeed Performance Report

Merging #8903 will not alter performance

_{Comparing fix-relative-and-join (9b64851) with main (dea6d62)}

🎉 Hooray! codspeed-rust just leveled up to 2.7.2!

A heads-up, this is a breaking change and it might affect your current performance baseline a bit. But here's the exciting part - it's packed with new, cool features and promises improved result stability 🥳!
Curious about what's new? Visit our releases page to delve into all the awesome details about this new version.

Summary

✅ 3 untouched benchmarks