Improve JSDoc coverage in gitlab-ui component code

We want to add comprehensive JSDoc comments to all props across all GitLab UI components to improve developer experience and documentation quality.

Benefits

• Enhanced Storybook documentation: JSDoc comments will automatically populate Storybook's controls and documentation panels, providing better context and examples for each prop
• Improved IDE support: The Vetur VSCode extension (and other IDE tools) will be able to provide more detailed autocomplete suggestions and inline documentation when developers use these components