Improved CLI argument handling using picocli

[patilatharva]

Objective

Use Picocli instead of Apache Commons CLI to parse command line options and parameters in Lfc.java, Lff.java and CliBase.java.

Reason

Migrating from Commons CLI to picocli

Tasks:

• Refactor CliBase.java to implement the Runnable interface, to support Picocli.
• Remove runMain in CliBase.java because Picocli handles simple validation and --help/--version options.
• Declare options as annotated fields and remove the CLIOption enum (Lfc.java/Lff.java).
• Implement the run() method as an entry point to post-argument parsing execution, in accordance with the Runnable interface (Lfc.java/Lff.java).
• Rewrite function filterProps into a new function filterPassOnProps to create code gen properties from Picocli options (CliBase.java).
• Refactoring for clarity: split runTool into runTool + invokeGenerator in Lfc.java, and runTool into runTool + formatAllFiles in Lff.java.
• Tweak CLI tests to support Picocli output syntax (e.g. "Unrecognized option" → "Unknown option").
• Ensure all tests on CI are passing.

[cmnrd]

This looks really great! Thanks for taking care of this refactoring. I left a few minor comments directly on the code.

[lhstrh]

Just resolved conflicts to trigger a CI run. Please check if I did it correctly :-)

[lhstrh]

This looks great, @patilatharva! I understood that you had started working on unit tests. Is that coming along or do you need help with those?

[lhstrh]

There are some strange test failures that are popping up, so this definitely needs some more work.

You can ignore the build failure in Maven for now. Either I'll push a fix for that or we punt on it and wait until the Maven build support gets removed from this repository (we only need it to build Epoch, which will soon be hosted in its own repo).

[patilatharva]

Just resolved conflicts to trigger a CI run. Please check if I did it correctly :-)

Thanks, looks good to me!

There are some strange test failures that are popping up, so this definitely needs some more work.

Definitely, looking into it now.

[tanneberger]

Looks good to me

[cmnrd]

This looks like a great improvement. I added a couple of comments, mostly small things. I hope we can resolve them quickly and merge this soon!

[cmnrd]

Updating review status to "request changes".

[cmnrd]

Thanks for your quick fixes! This is ready to be merged as far as I am concerned.

[lhstrh]

Please address the version TODO and once fixed we can merge this. Thanks, @patilatharva!