SPIGOT-3379: Generalise canPickupItems to other entities.

By: md_5 <git@md-5.net>

paper-server/nms-patches/EntityInsentient.patch

@@ -16,6 +16,15 @@
  public abstract class EntityInsentient extends EntityLiving {
  
      private static final DataWatcherObject<Byte> a = DataWatcher.a(EntityInsentient.class, DataWatcherRegistry.a);
+@@ -27,7 +36,7 @@
+     public float[] dropChanceHand;
+     private final NonNullList<ItemStack> by;
+     public float[] dropChanceArmor;
+-    public boolean canPickUpLoot;
++    // public boolean canPickUpLoot; // CraftBukkit - moved up to EntityLiving
+     public boolean persistent;
+     private final Map<PathType, Float> bB;
+     private MinecraftKey bC;
 @@ -57,6 +66,9 @@
              this.r();
          }