Support parsing optionals as positionals

[mauvilsa]

What does this PR do?

Fixes #690

Before submitting

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• 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 (64b6876) to head (9a4c92c).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #692   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           22        22           
  Lines         6694      6755   +61     
=========================================
+ Hits          6694      6755   +61     

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[Borda]

could we bump the version to an RC or something so I can test it with our CI - Lightning-AI/utilities#371

[mauvilsa]

could we bump the version to an RC or something so I can test it with our CI - Lightning-AI/utilities#371

This looks good https://github.com/Lightning-AI/utilities/blob/9610d5bfa0a639d0820ef525e5cec06b0db71e11/requirements/cli.txt#L1, I think there is no need for an RC.

[mauvilsa]

I have added more tests and documentation for the feature. But it is still pending to not support this for subclass and dataclass types. What to do regarding shtab can be a future improvement.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

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

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