Restore vanilla entity drops behavior

Instead of just tracking the itemstacks, this tracks with it, the
action to take with that itemstack to apply the correct logic
on dropping the item instead of generalizing it for all dropped
items like CB does.

paper-server/patches/sources/net/minecraft/world/entity/LivingEntity.java.patch

@@ -72,7 +72,7 @@
      protected float appliedScale;
 +    // CraftBukkit start
 +    public int expToDrop;
-+    public ArrayList<org.bukkit.inventory.ItemStack> drops = new ArrayList<org.bukkit.inventory.ItemStack>();
++    public ArrayList<DefaultDrop> drops = new ArrayList<>(); // Paper - Restore vanilla drops behavior
 +    public final org.bukkit.craftbukkit.attribute.CraftAttributeMap craftAttributes;
 +    public boolean collides = true;
 +    public Set<UUID> collidableExemptions = new HashSet<>();