DM-52711: Add support for structlog in time_this output

[timj]

This allows the duration itself to be sent as an explicit keyword value rather than being embedded in the text.

Checklist

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

[codecov]

Codecov Report

❌ Patch coverage is 91.37931% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.61%. Comparing base (ad6f798) to head (6a7f12e).
⚠️ Report is 6 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
python/lsst/utils/logging.py	76.92%	3 Missing ⚠️
tests/test_timer.py	93.10%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #232      +/-   ##
==========================================
- Coverage   94.66%   94.61%   -0.06%     
==========================================
  Files          51       51              
  Lines        3826     3880      +54     
==========================================
+ Hits         3622     3671      +49     
- Misses        204      209       +5     

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