SPIGOT-2706: Implement support for Lock NBT Tag

Containers may now implement the Lockable interface.

By: Senmori <thesenmori@gmail.com>

paper-api/src/main/java/org/bukkit/block/Dispenser.java

@@ -6,7 +6,7 @@ import org.bukkit.projectiles.BlockProjectileSource;
 /**
  * Represents a dispenser.
  */
-public interface Dispenser extends BlockState, InventoryHolder {
+public interface Dispenser extends BlockState, InventoryHolder, Lockable {
 
     /**
      * Gets the BlockProjectileSource object for this dispenser.