feat: introduce alias option support

[NamesMT]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Implements alias support using pathe's resolveAlias, similar to jiti and unbuild config.alias option

Related to unbuild regarding alias breaking/not working in mkdist builder
Related issues: #202, unjs/unbuild#375, unjs/unbuild#289

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[NamesMT]

Just realized mkdist doesn't transform aliases that point to srcDir into distDir, need a fix for that.
Edit: also would need to implement an absolute to relative import resolver to be usable.

How do I convert the PR to a draft? Update: DONE!

[NamesMT]

Seems usable now.

sorry for the light theme flash

[NamesMT]

Had some spare time to return to the PR and pushed a few more updates/fixes, such as CLI arg support and thorough case testing :D.

[NamesMT]

Hi @pi0, I did some more testing and the PR looks ready to ship,
Please help me review it when you have time, thanks!