feat(event): event.request getter to access web request

[pi0]

🔗 Linked issue

#73

❓ 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 the lazy initialized event.request property that resolves to a standard Web Request.

Note: It is still highly recommended to prefer using top level event API (event.{path,method,headers}) as it has lower foot print and can be optimized per runtime platform.

Known issues: Node.js 16 does not supports ReadableStream as body for Request constructor

Thanks for the initiative ideas from @Hebilicious in #421

📝 Checklist

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

[codecov]

Codecov Report

Merging #454 (9cf1a8d) into main (591836e) will increase coverage by 0.29%.
The diff coverage is 94.23%.

@@            Coverage Diff             @@
##             main     #454      +/-   ##
==========================================
+ Coverage   77.93%   78.23%   +0.29%     
==========================================
  Files          26       26              
  Lines        2724     2775      +51     
  Branches      398      407       +9     
==========================================
+ Hits         2123     2171      +48     
- Misses        601      604       +3     

Impacted Files	Coverage Δ
src/event/event.ts	74.40% <94.23%> (+6.28%)	⬆️