Implement getNMSWorld on EntityMinecartContainer

Was missed because the class is abstract and nothing implementing the class was imported in Paper

Spigot-Server-Patches/LootTable-API-Replenishable-Lootables-Feature.patch

@@ -483,6 +483,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        return lootableData;
 +    }
 +
++    @Override
++    public World getNMSWorld() {
++        return this.world;
++    }
++
 +    public String getLootTableName() {
 +        final MinecraftKey key = getLootTableKey();
 +        return key != null ? key.toString() : null;