fix: add parent node_modules of nitro to modules dir for pnpm compat

[pi0]

🔗 Linked issue

resolves unjs/nitro-deploys#83

❓ 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

Nitro installed in an external repository and with pnpm, adds rootDir/node_modules + rootDir/node_modules/.pnpm/nitropack-edge@2.6.0-28209634.345d0cc/node_modules/nitropack-edge/node_modules to the search path because of pnpm behavior and this causes the nitro direct runtime dependencies to fail to resolve.

This PR fixes it by also adding outer node_modules dir available for search and removed old dedup logic since is no longer necessary.

📝 Checklist

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

[codecov]

Codecov Report

Merging #1618 (9dca8e3) into main (8d7e660) will decrease coverage by 0.10%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1618      +/-   ##
==========================================
- Coverage   77.79%   77.69%   -0.10%     
==========================================
  Files          76       76              
  Lines        7835     7823      -12     
  Branches      804      799       -5     
==========================================
- Hits         6095     6078      -17     
- Misses       1738     1742       +4     
- Partials        2        3       +1     

Files Changed	Coverage Δ
src/options.ts	96.97% <100.00%> (+0.32%)	⬆️

... and 2 files with indirect coverage changes