New option in CLI to provide subcommands help when components given in a dict

[mauvilsa]

What does this PR do?

Implements Lightning-AI/litgpt#996 (comment)

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• Did you read the contributing guideline?
• 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 (028131c) to head (a83cb6b).

❗ Current head a83cb6b differs from pull request most recent head 2ab9994. Consider uploading reports for the commit 2ab9994 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #485      +/-   ##
===========================================
+ Coverage   99.98%   100.00%   +0.01%     
===========================================
  Files          21        21              
  Lines        6017      6016       -1     
===========================================
  Hits         6016      6016              
+ Misses          1         0       -1     

Flag	Coverage Δ
py3.10	88.41% <100.00%> (+0.01%)	⬆️
py3.10_all	98.73% <100.00%> (+0.01%)	⬆️
py3.10_pydantic1	48.90% <0.00%> (-0.05%)	⬇️
py3.10_pydantic2	48.62% <0.00%> (-0.05%)	⬇️
py3.10_types	98.73% <100.00%> (+0.01%)	⬆️
py3.11	88.39% <100.00%> (+0.72%)	⬆️
py3.11_all	98.73% <100.00%> (+0.91%)	⬆️
py3.11_types	98.73% <100.00%> (+0.91%)	⬆️
py3.12	88.39% <100.00%> (+0.01%)	⬆️
py3.12_all	98.73% <100.00%> (+0.01%)	⬆️
py3.12_types	98.73% <100.00%> (+0.01%)	⬆️
py3.7	88.98% <100.00%> (+0.01%)	⬆️
py3.7_all	99.49% <100.00%> (+0.01%)	⬆️
py3.7_types	99.48% <100.00%> (+0.01%)	⬆️
py3.8	89.12% <100.00%> (+0.01%)	⬆️
py3.8_all	99.51% <100.00%> (+0.01%)	⬆️
py3.8_types	99.50% <100.00%> (+0.01%)	⬆️
py3.9	88.97% <100.00%> (+0.01%)	⬆️
py3.9_all	99.38% <100.00%> (+0.01%)	⬆️
py3.9_types	99.38% <100.00%> (+0.01%)	⬆️

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud