src: use UTF-8 for task runner filesystem paths

[Archkon]

Use ConvertPathToUTF8() instead of path::string() when passing filesystem paths to Node and libuv interfaces. This prevents paths containing characters outside the active Windows code page from being corrupted or rejected.

[Archkon]

ping @StefanStojanovic

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.17%. Comparing base (bec3d0b) to head (a91aeff).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_task_runner.cc	83.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #64868      +/-   ##
==========================================
+ Coverage   90.14%   90.17%   +0.02%     
==========================================
  Files         746      746              
  Lines      242763   242763              
  Branches    45761    45765       +4     
==========================================
+ Hits       218848   218901      +53     
+ Misses      15402    15346      -56     
- Partials     8513     8516       +3     

Files with missing lines	Coverage Δ
src/node_task_runner.cc	89.32% <83.33%> (ø)

... and 36 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[anonrig]

Please add a test case