feat: stackblitz auto url detection (experimental)

[pi0]

🔗 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

This PR enables an experimental behavior where as we auto-detect publicURL for stack blitz environment and show it in CLI output.

This is a really hacky implementation implicitly based on internal behavior and environment variables (and naming) of stackblitz. I will have to check with their team how to improve (or remove it!)

https://stackblitz.com/~/github.com/unjs/listhen/pull/99

📝 Checklist

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

[codecov]

Codecov Report

Merging #99 (c304b18) into main (70cc93a) will increase coverage by 0.26%.
The diff coverage is 59.64%.

@@            Coverage Diff             @@
##             main      #99      +/-   ##
==========================================
+ Coverage   49.67%   49.93%   +0.26%     
==========================================
  Files          10       10              
  Lines        1516     1568      +52     
  Branches      101      108       +7     
==========================================
+ Hits          753      783      +30     
- Misses        763      785      +22     

Files Changed	Coverage Δ
src/server/dev.ts	7.46% <0.00%> (-0.04%)	⬇️
src/server/watcher.ts	14.70% <0.00%> (-0.45%)	⬇️
src/_utils.ts	56.09% <59.09%> (+3.46%)	⬆️
src/listen.ts	83.33% <100.00%> (+0.22%)	⬆️
src/types.ts	100.00% <100.00%> (ø)