feat: support prerendering binary files

[danielroe]

🔗 Linked issue

#319

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 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)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This supports writing prerendered responses as binary data directly.

To resolve #319 fully, we also need to support returning binary data in unenv rather than always coercing it to a string. (unjs/unenv#43).

📝 Checklist

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

[codecov]

Codecov Report

Merging #320 (44cf13f) into main (cc8527a) will decrease coverage by 0.04%.
The diff coverage is 60.00%.

❗ Current head 44cf13f differs from pull request most recent head b2635ce. Consider uploading reports for the commit b2635ce to get more accurate results

@@            Coverage Diff             @@
##             main     #320      +/-   ##
==========================================
- Coverage   53.57%   53.53%   -0.05%     
==========================================
  Files          54       54              
  Lines        3494     3495       +1     
  Branches      368      369       +1     
==========================================
- Hits         1872     1871       -1     
- Misses       1267     1268       +1     
- Partials      355      356       +1     

Impacted Files	Coverage Δ
src/types/nitro.ts	100.00% <ø> (ø)
src/utils/index.ts	22.22% <0.00%> (-1.31%)	⬇️
src/prerender.ts	67.56% <100.00%> (+0.22%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.