src: coerce spawnSync args to string once

[aduh95]

This also fixes a TOCTOU race condition for objects with non-constant toString returned value.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/72557/

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 89.78%. Comparing base (ae1c0e4) to head (e3aa3a3).
⚠️ Report is 32 commits behind head on main.

Files with missing lines	Patch %	Lines
src/spawn_sync.cc	90.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62633      +/-   ##
==========================================
- Coverage   89.79%   89.78%   -0.01%     
==========================================
  Files         697      697              
  Lines      215773   215771       -2     
  Branches    41297    41298       +1     
==========================================
- Hits       193749   193729      -20     
- Misses      14117    14132      +15     
- Partials     7907     7910       +3     

Files with missing lines	Coverage Δ
src/spawn_sync.cc	68.92% <90.00%> (+0.32%)	⬆️

... and 43 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/72559/