HHH-12133 - Create ManagedBeanRegistry and ManagedBean

- mostly just backporting this work from 6.0

hibernate-core/src/main/java/org/hibernate/resource/beans/internal/CompositeManagedBeanRegistry.java

@@ -86,6 +86,10 @@ public class CompositeManagedBeanRegistry
 		return fallback.getBean( beanName, beanContract,shouldRegistryManageLifecycle );
 	}
 
+	@Override
+	public ManagedBeanRegistry getPrimaryBeanRegistry() {
+		return primaryRegistry;
+	}
 
 	// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 	// Optional delegation

hibernate-core/src/main/java/org/hibernate/resource/beans/spi/ManagedBeanRegistry.java

@@ -46,4 +46,8 @@ public interface ManagedBeanRegistry extends Service {
 	 * the release calls itself.
 	 */
 	<T> ManagedBean<T> getBean(String beanName, Class<T> beanContract, boolean shouldRegistryManageLifecycle);
+
+	default ManagedBeanRegistry getPrimaryBeanRegistry() {
+		return this;
+	}
 }