fix horse inventories

Horse inventories now combine 2 inventories (like
result inventories).

== AT ==
public net/minecraft/world/inventory/HorseInventoryMenu SLOT_BODY_ARMOR

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftAbstractHorse.java

@@ -112,7 +112,7 @@ public abstract class CraftAbstractHorse extends CraftAnimals implements Abstrac
 
     @Override
     public AbstractHorseInventory getInventory() {
-        return new CraftSaddledInventory(getHandle().inventory);
+        return new CraftSaddledInventory(getHandle().inventory, this.getHandle().getBodyArmorAccess()); // Paper - use both inventories
     }
 
     // Paper start - Horse API