#21980 Fix Component/Relationship derive using non fully qualified path

[HeartofPhos]

Objective

Fixes #21980

Solution

Use fully qualified path for Entity

Testing

The following code now compiles

mod test {
    fn derive_component_relationship_hygiene() {
        #[derive(Debug, bevy::prelude::Component)]
        #[relationship(relationship_target = RelTarget)]
        struct Rel(pub bevy::prelude::Entity);

        #[derive(Debug, bevy::prelude::Component)]
        #[relationship_target(relationship = Rel)]
        struct RelTarget(bevy::prelude::Entity);
    }
}```