Expanded subcommand management API.

[kmvanbrunt]

1. Detaching a subcommand returns metadata for easily reattaching later
2. Added ability to remove all subcommands of a given command

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.53%. Comparing base (5b3bc53) to head (ced8042).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1663      +/-   ##
==========================================
- Coverage   99.55%   99.53%   -0.02%     
==========================================
  Files          22       22              
  Lines        4889     4934      +45     
==========================================
+ Hits         4867     4911      +44     
- Misses         22       23       +1     

Flag	Coverage Δ
unittests	99.53% <100.00%> (-0.02%)	⬇️

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[tleonhardt]

The test_proc_reader_terminate test is failing due to a timeout specifically for Window and Python 3.10. It may be a one-off fluke or it might not be.

I don't think I'd worry about it for this PR unless you have insight into what might be causing it.

We talked earlier today about dropping support for Python 3.10 in the upcoming 4.0.0 release and I am fully in support of that. I think we should do that in a separate PR.