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/0419-Add-BellRingEvent.patch

@@ -0,0 +1,25 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Eearslya Sleiarion <eearslya@gmail.com>
+Date: Sun, 23 Aug 2020 13:04:02 +0200
+Subject: [PATCH] Add BellRingEvent
+
+Add a new event, BellRingEvent, to trigger whenever a player rings a
+village bell. Passes along the bell block and the player who rang it.
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+index 67bfd38bd08c30eae597a4875ea4a8b26c2f5c5a..c045e9503c76b869d58d93077fef130759615ff5 100644
+--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
++++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+@@ -367,10 +367,11 @@ public class CraftEventFactory {
+         return tradeSelectEvent;
+     }
+ 
++    @SuppressWarnings("deprecation") // Paper use deprecated event to maintain compat (it extends modern event)
+     public static boolean handleBellRingEvent(Level world, BlockPos position, Direction direction, Entity entity) {
+         Block block = CraftBlock.at(world, position);
+         BlockFace bukkitDirection = CraftBlock.notchToBlockFace(direction);
+-        BellRingEvent event = new BellRingEvent(block, bukkitDirection, (entity != null) ? entity.getBukkitEntity() : null);
++        BellRingEvent event = new io.papermc.paper.event.block.BellRingEvent(block, bukkitDirection, (entity != null) ? entity.getBukkitEntity() : null); // Paper - deprecated BellRingEvent
+         Bukkit.getPluginManager().callEvent(event);
+         return !event.isCancelled();
+     }