Made iron golems fire CreatureSpawn event. Fixes BUKKIT-1089

By: EvilSeph <evilseph@gmail.com>

paper-api/src/main/java/org/bukkit/event/entity/CreatureSpawnEvent.java

@@ -120,6 +120,14 @@ public class CreatureSpawnEvent extends EntityEvent implements Cancellable {
          * When a snowman is spawned by being built
          */
         BUILD_SNOWMAN,
+        /**
+         * When an iron golem is spawned by being built
+         */
+        BUILD_IRONGOLEM,
+        /**
+         * When an iron golem is spawned to defend a village
+         */
+        VILLAGE_DEFENSE,
         /**
          * When a creature is manually spawned
          */