Modify components to allow application of more expressive styling.

[jgindin]

Description

A few components needed some tweaks in order to apply a new theme.

There is no change to these components when using existing themes.

Pre-launch Checklist

• [x ] I signed the CLA.
• [ x] I read the Contributors Guide.
• [ x] I read the Style Guide.
• I have added updates to the CHANGELOG.
• [ x] I updated/added relevant documentation.
• [ x] My code changes (if any) have tests.

[gemini-code-assist]

Code Review

This pull request updates the List, Slider, and Tabs components to support more expressive styling. While the changes introduce useful features and refactorings, there are a few issues to address. Most importantly, tests are missing for the new changes, which is required by the repository's contribution guidelines. Additionally, there are opportunities to improve type safety in the List component by avoiding $any(), and to reduce code duplication in the Slider component. I've also noted a minor formatting issue. Please see the specific comments for details.

[gemini-code-assist]

The repository style guide requires tests for code changes. While the PR description checklist for tests is marked as complete, I don't see any new or updated tests in this pull request. Please add unit tests to cover the new logic and behavior introduced in the List, Slider, and Tabs components.

References

1. If there are code changes, code should have tests. ^(link)

[ditman]

Some questions about some of the "hardcoded" classnames for the elements