cli: debug optional args

[Borda]

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did all existing and newly added tests pass locally?

What does this PR do?

Adding tests and fixing #371

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in GitHub issues there's a high chance it will not be merged.

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📚 Documentation preview 📚: https://lit-utilities--420.org.readthedocs.build/en/420/

[Copilot]

Pull Request Overview

This PR adds comprehensive test coverage for the CLI functionality and fixes argument parsing to support both positional and optional argument styles. The changes ensure that CLI commands can be invoked with either style consistently.

• Adds parametrized tests to verify both positional and optional argument parsing for all CLI commands
• Modifies the CLI configuration to disable positional-only parsing by setting as_positional=False
• Improves test structure with helper methods for building commands and creating test files

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
tests/unittests/cli/test_command_line.py	Adds comprehensive test suite with parametrized tests for both positional and optional argument styles
src/lightning_utilities/cli/main.py	Updates CLI configuration to support optional arguments by setting as_positional=False