Enhance manim cfg show output and add info-level logging for config files read

[xnov18]

Overview: What does this pull request change?

This pull request improves the manim cfg show command to display the config files read by Manim. It also adds info-level logging during startup to log which configuration files are actually loaded.

Motivation and Explanation: Why and how do your changes improve the library?

As a beginner open source contributor, I was searching for good first issues to jump in and solve. I implemented this feature to enhance transparency around Manim’s configuration loading. Specifically, I added info-level logging statements in the configuration parser function to log every config file as it is read, and updated the manim cfg show command to print the list of config files found before displaying their contents. This makes it easier for others to understand which configuration files are actually being used and helps with debugging any configuration-related problems.

Links to added or changed documentation pages

No documentation was changed.

Further Information and Comments

This PR addresses issue #4369

Reviewer Checklist

• The PR title is descriptive enough for the changelog, and the PR is labeled correctly
• If applicable: newly added non-private functions and classes have a docstring including a short summary and a PARAMETERS section
• If applicable: newly added functions and classes are tested

[behackl]

Thanks for your contribution, this seems fine to me!