Current Chunk for Entity and Block Entities, counts by entity type

This enables us a fast reference to the entities current chunk instead
of having to look it up by hashmap lookups.

We also store counts by type to further enable other performance optimizations in later patches.

Spigot-Server-Patches/Fix-Old-Sign-Conversion.patch

@@ -34,11 +34,11 @@ index 9f314204b..23da9467e 100644
  
          public Iterator<IBlockData> iterator() {
 diff --git a/src/main/java/net/minecraft/server/TileEntity.java b/src/main/java/net/minecraft/server/TileEntity.java
-index 65297a761..537e4b155 100644
+index dfdc55583..d3bc13726 100644
 --- a/src/main/java/net/minecraft/server/TileEntity.java
 +++ b/src/main/java/net/minecraft/server/TileEntity.java
 @@ -0,0 +0,0 @@ import org.bukkit.inventory.InventoryHolder; // CraftBukkit
- public abstract class TileEntity {
+ public abstract class TileEntity implements KeyedObject {
  
      public Timing tickTimer = MinecraftTimings.getTileEntityTimings(this); // Paper
 +    boolean isLoadingStructure = false; // Paper