component_preview: Clean up `Component` trait (#57731)

This primarily
- requires components to have a description as well as a preview
(especially having no preview makes no sense)
- implements some basic previews where missing
- adds a scrollbar to the preview navigation 

with a sadly large diff due to reformatting (less indentation 🎉 ), but
very little changes at its core.

Release Notes:

- N/A
e4b81180c1Finn Evers committed on 5/29/2026, 7:06:57 AM· committed by GitHubparentaeb5d6d
63 files changedLine totals unavailable