Extract UI elements from storybook into new ui crate (#3008)

This PR extracts the various UI elements from the `storybook` crate into
a new `ui` library crate.

Release Notes:

- N/A

crates/ui/src/elements.rs

@@ -0,0 +1,19 @@
+mod avatar;
+mod details;
+mod icon;
+mod icon_button;
+mod indicator;
+mod input;
+mod label;
+mod text_button;
+mod tool_divider;
+
+pub use avatar::*;
+pub use details::*;
+pub use icon::*;
+pub use icon_button::*;
+pub use indicator::*;
+pub use input::*;
+pub use label::*;
+pub use text_button::*;
+pub use tool_divider::*;