SPIGOT-4943: Zombie villager conversion player API.

Also resetting the conversion player when stopping a conversion.

By: blablubbabc <lukas@wirsindwir.de>

paper-server/nms-patches/EntityZombieVillager.patch

@@ -1,6 +1,6 @@
 --- a/net/minecraft/server/EntityZombieVillager.java
 +++ b/net/minecraft/server/EntityZombieVillager.java
-@@ -3,6 +3,10 @@
+@@ -3,15 +3,20 @@
  import com.mojang.datafixers.Dynamic;
  import java.util.UUID;
  import javax.annotation.Nullable;
@@ -11,8 +11,11 @@
  
  public class EntityZombieVillager extends EntityZombie implements VillagerDataHolder {
  
-@@ -12,6 +16,7 @@
-     private UUID conversionPlayer;
+     public static final DataWatcherObject<Boolean> CONVERTING = DataWatcher.a(EntityZombieVillager.class, DataWatcherRegistry.i);
+     private static final DataWatcherObject<VillagerData> c = DataWatcher.a(EntityZombieVillager.class, DataWatcherRegistry.q);
+     public int conversionTime;
+-    private UUID conversionPlayer;
++    public UUID conversionPlayer; // CraftBukkit - public
      private NBTTagCompound bB;
      private int bC;
 +    private int lastTick = MinecraftServer.currentTick; // CraftBukkit - add field