ui: More component previews, UI component cleanup (#25302)

- Don't require ui component docs (this isn't really working)
- Add more component previews
- Update component preview style & navigation

Release Notes:

- N/A

crates/ui/src/components/image.rs

@@ -1,4 +1,3 @@
-#![allow(missing_docs)]
 use gpui::{svg, App, IntoElement, Rems, RenderOnce, Size, Styled, Window};
 use serde::{Deserialize, Serialize};
 use strum::{EnumIter, EnumString, IntoStaticStr};