Add key for item model (#2572)

* Add key for item model

* Add a link to the wiki

* Update MODEL Javadoc

Author: avaruus1

src/main/java/org/spongepowered/api/data/Keys.java

@@ -2437,6 +2437,13 @@ public final class Keys {
      */
     public static final Key<Value<Ticks>> MIN_SPAWN_DELAY = Keys.key(ResourceKey.sponge("min_spawn_delay"), Ticks.class);
 
+    /**
+     * Location of the resource pack model for an {@link ItemStack}.
+     *
+     * @see <a href="https://minecraft.wiki/w/Model">Model</a>
+     */
+    public static final Key<Value<ResourceKey>> MODEL = Keys.key(ResourceKey.sponge("model"), ResourceKey.class);
+
     /**
      * The moisture value of a {@link BlockTypes#FARMLAND} {@link BlockState}.
      */