Previously reflection was required when interacting with Hibernate 4 in
order to support both Hibernate 3 and Hibernate 4 since there were
non-passive changes in the APIs. Now that the Spring build uses Gradle
it is trivial to support multiple Hibernate versions.

This commit removes the reflection usage in orm.hibernate4.* by
creating a spring-orm-hibernate4 module that uses
gradle/merge-artifacts.gradle to build a single artifact but keep
distinct classpaths.

Issue: SPR-10039