Merge Component and ComponentPreview trait (#28365)

- Merge `Component` and `ComponentPreview` trait
- Adds a number of component previews
- Removes a number of stories

Release Notes:

- N/A

crates/ui_macros/src/derive_register_component.rs

@@ -0,0 +1,25 @@
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{DeriveInput, parse_macro_input};
+
+pub fn derive_register_component(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+    let name = input.ident;
+    let reg_fn_name = syn::Ident::new(
+        &format!("__component_registry_internal_register_{}", name),
+        name.span(),
+    );
+    let expanded = quote! {
+        const _: () = {
+            struct AssertComponent<T: component::Component>(::std::marker::PhantomData<T>);
+            let _ = AssertComponent::<#name>(::std::marker::PhantomData);
+        };
+
+        #[allow(non_snake_case)]
+        #[linkme::distributed_slice(component::__ALL_COMPONENTS)]
+        fn #reg_fn_name() {
+            component::register_component::<#name>();
+        }
+    };
+    expanded.into()
+}

crates/ui_macros/src/ui_macros.rs

@@ -1,5 +1,5 @@
-mod derive_component;
 mod derive_path_str;
+mod derive_register_component;
 mod dynamic_spacing;
 
 use proc_macro::TokenStream;
@@ -60,26 +60,28 @@ pub fn derive_dynamic_spacing(input: TokenStream) -> TokenStream {
     dynamic_spacing::derive_spacing(input)
 }
 
-/// Derives the `Component` trait for a struct.
+/// Registers components that implement the `Component` trait.
 ///
-/// This macro generates implementations for the `Component` trait and associated
-/// registration functions for the component system.
+/// This proc macro is used to automatically register structs that implement
+/// the `Component` trait with the [`component::ComponentRegistry`].
 ///
-/// # Attributes
-///
-/// - `#[component(scope = "...")]`: Required. Specifies the scope of the component.
-/// - `#[component(description = "...")]`: Optional. Provides a description for the component.
+/// If the component trait is not implemented, it will generate a compile-time error.
 ///
 /// # Example
 ///
 /// ```
-/// use ui_macros::Component;
+/// use ui_macros::RegisterComponent;
 ///
-/// #[derive(Component)]
-/// #[component(scope = "toggle", description = "A element that can be toggled on and off")]
-/// struct Checkbox;
+/// #[derive(RegisterComponent)]
+/// struct MyComponent;
+///
+/// impl Component for MyComponent {
+///     // Component implementation
+/// }
 /// ```
-#[proc_macro_derive(IntoComponent, attributes(component))]
-pub fn derive_component(input: TokenStream) -> TokenStream {
-    derive_component::derive_into_component(input)
+///
+/// This example will add MyComponent to the ComponentRegistry.
+#[proc_macro_derive(RegisterComponent)]
+pub fn derive_register_component(input: TokenStream) -> TokenStream {
+    derive_register_component::derive_register_component(input)
 }