Attribute Macro lockjaw::module_attributes::multibinds

#[multibinds]

Declares that a Vec<T> or HashMap<K,V> is a multibinding.

If #[into_vec]/#[elements_into_vec]/ #[into_map] exists in the same graph this is not necessary, but if the collection is empty lockjaw needs to know that it is indeed a multibinding collection that is currently empty, instead of the user trying to depend on a type that is not bound.