Store failed jobs and add cleanup

[adam-fowler]

Also store paused jobs separately, and reset stopping flag at start up
This is so I can test re-running workflows
Upped default for numWorkers to 16

[codecov]

Codecov Report

❌ Patch coverage is 54.76190% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.54%. Comparing base (6dd9e8e) to head (13ab695).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
Sources/Jobs/MemoryJobQueue.swift	54.76%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #126      +/-   ##
==========================================
- Coverage   86.67%   85.54%   -1.14%     
==========================================
  Files          25       25              
  Lines        1336     1363      +27     
==========================================
+ Hits         1158     1166       +8     
- Misses        178      197      +19     

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