add pre-shutdown action to be executed inside ChronicleHashCloseOnExitHook.

This is useful when we want to do an orderly shutdown.
For example: To carry out graceful shutdown and explicitly control when a ChronicleHash
is closed, a pre-shutdown action can be a wait on a CountDownLatch that would be released
appropriately.

src/main/java/net/openhft/chronicle/set/ChronicleSetBuilder.java

@@ -353,6 +353,11 @@ public final class ChronicleSetBuilder<K>
         return new SetFromMap<>((VanillaChronicleMap<K, DummyValue, ?>) map);
     }
 
+    @Override
+    public void setPreShutdownAction(Runnable preShutdownAction) {
+        chronicleMapBuilder.setPreShutdownAction(preShutdownAction);
+    }
+
     /**
      * @deprecated don't use private API in the client code
      */