src: add watch config namespace

[marco-ippolito]

watch is a pain to test 😿 working on it

[nodejs-github-bot]

Review requested:

• @nodejs/config

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 88.56%. Comparing base (d9b8a35) to head (b335bff).
⚠️ Report is 67 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_options.cc	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #60178      +/-   ##
==========================================
+ Coverage   88.54%   88.56%   +0.02%     
==========================================
  Files         703      704       +1     
  Lines      207809   208323     +514     
  Branches    40009    40032      +23     
==========================================
+ Hits       184006   184504     +498     
- Misses      15819    15861      +42     
+ Partials     7984     7958      -26     

Files with missing lines	Coverage Δ
src/node_options.h	97.90% <ø> (ø)
src/node_options.cc	77.83% <0.00%> (ø)

... and 72 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/69777/