Allow ordering in the lookup of services in AddonRegistry

Some services may require to be executed before others. It would be nice if the container could order these services while an iteraction of an Imported object happens. This ordering may happen based on an annotation or an interface.

Eg: When an UIContextListener is returned from an Imported, the CommandScopedContext should be fired first, to allow @CommandScoped objects to exist before other UIContextListeners are fired.