ui: Introduce Banner component (#27853)

This PR adds a new, generic `Banner` component so that we can
potentially replace the multiple, isolated implementations of it
throughout some places of the app.

<img
src="https://github.com/user-attachments/assets/a268f745-1747-48e6-9461-2732eb7c0be4"
width="750"/>

Release Notes:

- N/A

crates/ui/src/components.rs

@@ -1,4 +1,5 @@
 mod avatar;
+mod banner;
 mod button;
 mod content_group;
 mod context_menu;
@@ -37,6 +38,7 @@ mod tooltip;
 mod stories;
 
 pub use avatar::*;
+pub use banner::*;
 pub use button::*;
 pub use content_group::*;
 pub use context_menu::*;