Adapt WildFly to use ModuleSpecification.getMutableUserDependencies returning a Collection interface

It is planned that ModuleSpecification.getMutableUserDependencies() will return a Collection instead of a List.

We need to review WildFly code and replace the List with a Collection when this method is invoked.

This method is public, but it is managed by a private API, so we do not need to deprecate them first on WildFly Core.