SPIGOT-1373: Implement EntityTargetEvent for TEMPT.

This can be a high frequency event call. Use with care.

By: md_5 <git@md-5.net>

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

@@ -142,6 +142,11 @@ public class EntityTargetEvent extends EntityEvent implements Cancellable {
          * entity
          */
         CLOSEST_ENTITY,
+        /**
+         * When another entity tempts this entity by having a desired item such
+         * as wheat in it's hand.
+         */
+        TEMPT,
         /**
          * A currently unknown reason for the entity changing target.
          */