enh: allow con-duct pp usage.json

[asmacdo]

Fixes #339

Draft because I think we are on the cusp of merging a large refactor #327

I'd rather fixup this one after that merges than delay that one

• add test

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.15%. Comparing base (e30a56c) to head (fdfed65).
⚠️ Report is 30 commits behind head on main.

Files with missing lines	Patch %	Lines
src/con_duct/suite/pprint_json.py	50.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #341      +/-   ##
==========================================
- Coverage   91.34%   91.15%   -0.19%     
==========================================
  Files           7        7              
  Lines         947      950       +3     
  Branches      125      126       +1     
==========================================
+ Hits          865      866       +1     
- Misses         59       60       +1     
- Partials       23       24       +1     

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[asmacdo]

Closing in favor of

• Use jsonl suffix and centralize json loading #344