The CLASS_PATH_OR_NAME for subclass help is now optional and if not given the help of the base class is printed

[mauvilsa]

What does this PR do?

Implements #624 (comment)

Before submitting

• Did you read the contributing guideline?
• [n/a] Did you update the documentation? (readme and public docstrings)
• Did you write unit tests such that there is 100% coverage on related code? (required for bug fixes and new features)
• Did you verify that new and existing tests pass locally?
• Did you make sure that all changes preserve backward compatibility?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or minor internal changes/refactors)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (a1137c1) to head (8207f48).

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #628   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           22        22           
  Lines         6490      6496    +6     
=========================================
+ Hits          6490      6496    +6     

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[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud