Add derive macros for Message and Resource marker type

[tynberry]

While, in terms of length, there isn't much of a difference between
#[derive(Resource)]
and
impl Resource for CoolType {}
it would produce cleaner code as impl blocks are usually bordered by empty lines and you could put it together with other derived traits.
Also, you can see if the trait is a resource/message at first glance instead of looking for a impl block somewhere.