Introduce VirtualIdEmbeddable and IdClassEmbeddable + instantiators

More clean-up (Tuplizers!!)

Mostly EntityTuplizer in this commit

Still need to
  - integrate EmbeddableInstantiator work
  - integrate embedded forms.  `VirtualIdEmbeddable` does not really need it as it can use the id-mapping itself as the embedded form.  But `IdClassEmbedded` should really be integrated
  - integrate `VirtualKeyEmbeddable` and `VirtualKeyEmbedded` for use as inverse composite fks
  - share `#finishInit` handling for `EmbeddableMappingType`, `VirtualIdEmbeddable` and `IdClassEmbeddable`

hibernate-core/src/main/java/org/hibernate/metamodel/spi/ManagedTypeRepresentationResolver.java

@@ -20,8 +20,6 @@
  * @apiNote Like ManagedTypeRepresentationStrategy itself, incubating because we
  * currently need to differentiate between strategy for entity/mapped-superclass
  * versus strategy for embeddables
- *
- * @author Steve Ebersole
  */
 @Incubating
 public interface ManagedTypeRepresentationResolver {

hibernate-core/src/main/java/org/hibernate/metamodel/spi/ManagedTypeRepresentationStrategy.java

@@ -24,7 +24,7 @@
  * both IdentifiableType and EmbeddableType types but that requires (planned)
  * changes to the Hibernate type system that will not happen until a later date
  *
- * @author Steve Ebersole
+ * @see ManagedTypeRepresentationResolver
  */
 @Incubating
 public interface ManagedTypeRepresentationStrategy {

hibernate-core/src/main/java/org/hibernate/tuple/Instantiator.java

@@ -11,8 +11,11 @@
 /**
  * Contract for implementors responsible for instantiating entity/component instances.
  *
- * @author Steve Ebersole
+ * @deprecated (as of 6.0) This contract is no longer used by Hibernate.  Implement/use
+ * {@link org.hibernate.metamodel.spi.Instantiator} instead.  See
+ * {@link org.hibernate.metamodel.spi.ManagedTypeRepresentationStrategy}
  */
+@Deprecated
 public interface Instantiator extends Serializable {
 
 	/**

hibernate-core/src/main/java/org/hibernate/tuple/PojoInstantiator.java

@@ -19,7 +19,10 @@
 import org.hibernate.mapping.Component;
 /**
  * Defines a POJO-based instantiator for use from the tuplizers.
+ *
+ * @deprecated (as of 6.0) Like {@link Instantiator} itself, deprecated.
  */
+@Deprecated
 public class PojoInstantiator implements Instantiator, Serializable {
 	private static final CoreMessageLogger LOG = CoreLogging.messageLogger( PojoInstantiator.class.getName() );
 
@@ -30,6 +33,10 @@ public class PojoInstantiator implements Instantiator, Serializable {
 	private final boolean embeddedIdentifier;
 	private final boolean isAbstract;
 
+	/**
+	 * @deprecated (as of 6.0) See {@link PojoInstantiator}
+	 */
+	@Deprecated
 	public PojoInstantiator(
 			Class mappedClass,
 			ReflectionOptimizer.InstantiationOptimizer optimizer,
@@ -48,10 +55,18 @@ public PojoInstantiator(
 		}
 	}
 
+	/**
+	 * @deprecated (as of 6.0) See {@link PojoInstantiator}
+	 */
+	@Deprecated
 	public PojoInstantiator(Component component, ReflectionOptimizer.InstantiationOptimizer optimizer) {
 		this( component.getComponentClass(), optimizer );
 	}
 
+	/**
+	 * @deprecated (as of 6.0) See {@link PojoInstantiator}
+	 */
+	@Deprecated
 	public PojoInstantiator(Class componentClass, ReflectionOptimizer.InstantiationOptimizer optimizer) {
 		this.mappedClass = componentClass;
 		this.isAbstract = ReflectHelper.isAbstractClass( mappedClass );