Improvements to BlockStates

* Update Javadoc of block state classes to better match implementation behaviour.
* Add Container interface which provides access to the snapshot inventory.

By: Lukas Hennig <lukas@wirsindwir.de>

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

@@ -1,9 +1,8 @@
 package org.bukkit.block;
 
 import org.bukkit.Nameable;
-import org.bukkit.inventory.InventoryHolder;
 
 /**
- * Represents a hopper.
+ * Represents a captured state of a hopper.
  */
-public interface Hopper extends BlockState, InventoryHolder, Lockable, Nameable { }
+public interface Hopper extends Container, Nameable { }