DM-42116: Fix numpydoc doc strings and enable validation

[timj]

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (d8b6bfa) 82.53% compared to head (fea2f20) 82.50%.
Report is 2 commits behind head on main.

❗ Current head fea2f20 differs from pull request most recent head 451cdb3. Consider uploading reports for the commit 451cdb3 to get more accurate results

Files	Patch %	Lines
python/lsst/pipe/base/cmdLineTask.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #395      +/-   ##
==========================================
- Coverage   82.53%   82.50%   -0.03%     
==========================================
  Files          92       92              
  Lines       10427    10428       +1     
  Branches     1971     1971              
==========================================
- Hits         8606     8604       -2     
- Misses       1480     1482       +2     
- Partials      341      342       +1     

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