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/0527-Add-fast-alternative-constructor-for-Rotations.patch

@@ -0,0 +1,29 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Irmo van den Berge <irmo.vandenberge@ziggo.nl>
+Date: Wed, 10 Mar 2021 21:26:31 +0100
+Subject: [PATCH] Add fast alternative constructor for Rotations
+
+
+diff --git a/src/main/java/net/minecraft/core/Rotations.java b/src/main/java/net/minecraft/core/Rotations.java
+index e4b4e78de933b93be87805501d9cbfec429cf68c..95ef904bebeaff3275f25c401ef13c68504f3514 100644
+--- a/src/main/java/net/minecraft/core/Rotations.java
++++ b/src/main/java/net/minecraft/core/Rotations.java
+@@ -19,6 +19,18 @@ public class Rotations {
+         this(serialized.getFloat(0), serialized.getFloat(1), serialized.getFloat(2));
+     }
+ 
++    // Paper start - faster alternative constructor
++    private Rotations(float x, float y, float z, Void dummy_var) {
++        this.x = x;
++        this.y = y;
++        this.z = z;
++    }
++
++    public static Rotations createWithoutValidityChecks(float x, float y, float z) {
++        return new Rotations(x, y, z, null);
++    }
++    // Paper end - faster alternative constructor
++
+     public ListTag save() {
+         ListTag listTag = new ListTag();
+         listTag.add(FloatTag.valueOf(this.x));