feat: support web streams

[pi0]

🔗 Linked issue

unjs/nitro#1327

❓ 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 adds support for sending Web Streams for Node.js and for Worker environments (only via unenv+nitro). Also enables tests.

Users can directly return a web stream in an event handler.

Notes:

• Support for workers is experimental
• Node.js 18 is required for global ReadableStream (Node.js 16 does not support Web Streams)

📝 Checklist

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

[codecov]

Codecov Report

Merging #432 (5224f03) into main (e359f5f) will decrease coverage by 1.34%.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##             main     #432      +/-   ##
==========================================
- Coverage   76.33%   75.00%   -1.34%     
==========================================
  Files          26       26              
  Lines        2502     2552      +50     
  Branches      354      365      +11     
==========================================
+ Hits         1910     1914       +4     
- Misses        592      638      +46     

Impacted Files	Coverage Δ
src/utils/response.ts	68.75% <87.50%> (+6.13%)	⬆️

... and 5 files with indirect coverage changes