Reflected traits for resources and components: bevy_a11y (#15192)

Solves #15187 for the bevy_a11y
subcrate.

crates/bevy_a11y/src/lib.rs

@@ -21,6 +21,7 @@ use bevy_ecs::{
     schedule::SystemSet,
     system::Resource,
 };
+use bevy_reflect::std_traits::ReflectDefault;
 use bevy_reflect::Reflect;
 
 /// Wrapper struct for [`accesskit::ActionRequest`]. Required to allow it to be used as an `Event`.
@@ -94,7 +95,7 @@ impl From<NodeBuilder> for AccessibilityNode {
 
 /// Resource representing which entity has keyboard focus, if any.
 #[derive(Resource, Default, Deref, DerefMut, Reflect)]
-#[reflect(Resource)]
+#[reflect(Resource, Default)]
 pub struct Focus(pub Option<Entity>);
 
 /// Set enum for the systems relating to accessibility