Fix TypeName resolution of method return type

[christophstrobl]

TypeNames.typeName does only return the name of the TypeVariable which is not sufficient in certain cases where we need to make sure to fully resolve the name.

Eg. like in the following scenario (also described in spring-projects/spring-data-jpa#4028).

public interface BaseRepository<T, ID> extends CrudRepository<T, ID> {

    T selectBy(ID id);

}
public interface SomeRepo extends BaseRepository<SomeType, Long> {

}



MethodParameter methodParameter = new MethodParameter(method, 0).withContainingClass(SomeRepo.class);
ResolvableType resolvableType = ResolvableType.forMethodParameter(methodParameter);

TypeNames.typeName(resolvableType) // -> ID