fix(logging): isolate CLI logging setup to avoid affecting library users

[JigyasuRajput]

Description:

Fixes #4559
This PR refactors the logging setup in cve-bin-tool to prevent unintended logging configuration when the package is used as a library. Specifically:

• Added NullHandler to the package logger in __init__.py to avoid “No handler found” warnings.
• Disabled logger propagation to prevent logs from bubbling up to the root logger.
• Removed default Rich logging setup from log.py.
• Introduced setup_rich_logger() to be explicitly called in CLI context.
• Updated cli.py to call setup_rich_logger() during CLI entry point execution.
• Added test_logging.py to validate that:
  • Package logger has a NullHandler
  • Root logger remains unmodified
  • No propagation occurs
  • setup_rich_logger() correctly adds a RichHandler

[joydeep049]

Hi @JigyasuRajput
I see that you have marked this PR as draft. Are you waiting for something to get merged first?

Also, feel free to have the CI re-run, since the CI issues have already been fixed.

[JigyasuRajput]

Hi @JigyasuRajput I see that you have marked this PR as draft. Are you waiting for something to get merged first?

Also, feel free to have the CI re-run, since the CI issues have already been fixed.

hey!
I marked it as a draft because "it was not ready for a review yet", I still might need to tweak some changes so the tests in the CI do pass, but thanks for the heads-up!
I'm still working on my other PR to get them merged (specially the issue we have with uc\ /lib) I'll soon update this branch with more changes.