Restructure storybook modules and components

Co-Authored-By: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>

crates/storybook/src/components.rs

@@ -4,6 +4,12 @@ use gpui2::{
 };
 use std::{marker::PhantomData, rc::Rc};
 
+mod icon_button;
+mod tab;
+
+pub(crate) use icon_button::{icon_button, ButtonVariant};
+pub(crate) use tab::tab;
+
 struct ButtonHandlers<V, D> {
     click: Option<Rc<dyn Fn(&mut V, &D, &mut EventContext<V>)>>,
 }