Allow enabling sand duping (#10191)

Because this exploit has been widely known for years and has not been fixed by Mojang, we decided that it was worth allowing people to toggle it on/off due to how easy it is to make it configurable.

It should be noted that this decision does not promise all future exploits will be configurable.

patches/server/0394-Add-BlockStateMeta-clearBlockState.patch

@@ -0,0 +1,24 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <jake.m.potrebic@gmail.com>
+Date: Thu, 11 Jan 2024 12:41:50 -0800
+Subject: [PATCH] Add BlockStateMeta#clearBlockState
+
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java
+index 0cbca0c37b3e6a34157906d44357286126cfe112..671a9b92da04c22cd3e6c3fd291a343e57397e72 100644
+--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java
++++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java
+@@ -257,6 +257,13 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
+         return this.blockEntityTag != null;
+     }
+ 
++    // Paper start - add method to clear block state
++    @Override
++    public void clearBlockState() {
++        this.blockEntityTag = null;
++    }
++    // Paper end - add method to clear block state
++
+     @Override
+     public BlockState getBlockState() {
+         Material stateMaterial = (this.material != Material.SHIELD) ? this.material : CraftMetaBlockState.shieldToBannerHack(this.blockEntityTag); // Only actually used for jigsaws