feat: detect stackblitz using process.versions.webcontainer

[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

Improve stackblitz/webcontainer environment detection based on process.versions.webcontainer.

PS: I really hope someday soon Stackblitz standard environment variables to make us able to detect running environment easier..

📝 Checklist

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

[codecov]

Codecov Report

Merging #63 (e728741) into main (25cdeec) will increase coverage by 0.06%.
Report is 1 commits behind head on main.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #63      +/-   ##
==========================================
+ Coverage   82.82%   82.88%   +0.06%     
==========================================
  Files           6        6              
  Lines         262      263       +1     
  Branches       25       25              
==========================================
+ Hits          217      218       +1     
  Misses         42       42              
  Partials        3        3              

Files Changed	Coverage Δ
src/flags.ts	100.00% <100.00%> (ø)
src/providers.ts	90.00% <100.00%> (+0.07%)	⬆️