Improve the Saddle API for Horses

Not all horses with Saddles have armor. This lets us break up the horses with saddles
and access their saddle state separately from an interface shared with Armor.

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

@@ -5,6 +5,7 @@ import java.util.UUID;
 import net.minecraft.world.entity.ai.attributes.Attributes;
 import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.craftbukkit.inventory.CraftInventoryAbstractHorse;
+import org.bukkit.craftbukkit.inventory.CraftSaddledInventory;
 import org.bukkit.entity.AbstractHorse;
 import org.bukkit.entity.AnimalTamer;
 import org.bukkit.entity.Horse;
@@ -107,6 +108,6 @@ public abstract class CraftAbstractHorse extends CraftAnimals implements Abstrac
 
     @Override
     public AbstractHorseInventory getInventory() {
-        return new CraftInventoryAbstractHorse(this.getHandle().inventory);
+        return new CraftSaddledInventory(getHandle().inventory);
     }
 }

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryHorse.java

@@ -4,7 +4,7 @@ import net.minecraft.world.Container;
 import org.bukkit.inventory.HorseInventory;
 import org.bukkit.inventory.ItemStack;
 
-public class CraftInventoryHorse extends CraftInventoryAbstractHorse implements HorseInventory {
+public class CraftInventoryHorse extends CraftSaddledInventory implements HorseInventory {
 
     private final Container bodyArmorInventory;
 

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftSaddledInventory.java

@@ -0,0 +1,12 @@
+package org.bukkit.craftbukkit.inventory;
+
+import net.minecraft.world.Container;
+import org.bukkit.inventory.SaddledHorseInventory;
+
+public class CraftSaddledInventory extends CraftInventoryAbstractHorse implements SaddledHorseInventory {
+
+    public CraftSaddledInventory(Container inventory) {
+        super(inventory);
+    }
+
+}