Improve death events

This adds the ability to cancel the death events and to modify the sound
an entity makes when dying. (In cases were no sound should it will be
called with shouldPlaySound set to false allowing unsilencing of silent
entities)

It makes handling of entity deaths a lot nicer as you no longer need
to listen on the damage event and calculate if the entity dies yourself
to cancel the death which has the benefit of also receiving the dropped
items and experience which is otherwise only properly possible by using
internal code.

== AT ==
public net.minecraft.world.entity.LivingEntity getDeathSound()Lnet/minecraft/sounds/SoundEvent;
public net.minecraft.world.entity.LivingEntity getSoundVolume()F

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

@@ -279,7 +279,42 @@
          ProfilerFiller gameprofilerfiller = Profiler.get();
  
          gameprofilerfiller.push("sensing");
-@@ -1338,7 +1444,7 @@
+@@ -1011,6 +1117,12 @@
+ 
+     }
+ 
++    // Paper start
++    protected boolean shouldSkipLoot(EquipmentSlot slot) { // method to avoid to fallback into the global mob loot logic (i.e fox)
++        return false;
++    }
++    // Paper end
++
+     @Override
+     protected void dropCustomDeathLoot(ServerLevel world, DamageSource source, boolean causedByPlayer) {
+         super.dropCustomDeathLoot(world, source, causedByPlayer);
+@@ -1018,6 +1130,7 @@
+ 
+         while (iterator.hasNext()) {
+             EquipmentSlot enumitemslot = (EquipmentSlot) iterator.next();
++            if (this.shouldSkipLoot(enumitemslot)) continue; // Paper
+             ItemStack itemstack = this.getItemBySlot(enumitemslot);
+             float f = this.getEquipmentDropChance(enumitemslot);
+ 
+@@ -1042,7 +1155,13 @@
+                     }
+ 
+                     this.spawnAtLocation(world, itemstack);
++                    if (this.clearEquipmentSlots) { // Paper
+                     this.setItemSlot(enumitemslot, ItemStack.EMPTY);
++                    // Paper start
++                    } else {
++                        this.clearedEquipmentSlots.add(enumitemslot);
++                    }
++                    // Paper end
+                 }
+             }
+         }
+@@ -1338,7 +1457,7 @@
          if (itemstack.getItem() instanceof SpawnEggItem) {
              if (this.level() instanceof ServerLevel) {
                  SpawnEggItem itemmonsteregg = (SpawnEggItem) itemstack.getItem();
@@ -288,7 +323,7 @@
  
                  optional.ifPresent((entityinsentient) -> {
                      this.onOffspringSpawnedFromEgg(player, entityinsentient);
-@@ -1389,28 +1495,51 @@
+@@ -1389,28 +1508,51 @@
          return this.restrictRadius != -1.0F;
      }
  
@@ -321,13 +356,13 @@
 +                conversionparams.type().convert(this, t0, conversionparams);
 +                if (!conversionparams_a.finalizeConversionOrCancel(t0)) return null; // Paper - entity zap event - return null if conversion was cancelled
                  Level world = this.level();
- 
++
 +                // CraftBukkit start
 +                if (transformReason == null) {
 +                    // Special handling for slime split and pig lightning
 +                    return t0;
 +                }
-+
+ 
 +                if (CraftEventFactory.callEntityTransformEvent(this, t0, transformReason).isCancelled()) {
 +                    return null;
 +                }
@@ -346,7 +381,7 @@
                  }
  
                  return t0;
-@@ -1420,10 +1549,22 @@
+@@ -1420,10 +1562,22 @@
  
      @Nullable
      public <T extends Mob> T convertTo(EntityType<T> entityType, ConversionParams context, ConversionParams.AfterConversion<T> finalizer) {
@@ -370,7 +405,7 @@
      @Override
      public Leashable.LeashData getLeashData() {
          return this.leashData;
-@@ -1458,6 +1599,7 @@
+@@ -1458,6 +1612,7 @@
          boolean flag1 = super.startRiding(entity, force);
  
          if (flag1 && this.isLeashed()) {
@@ -378,7 +413,7 @@
              this.dropLeash();
          }
  
-@@ -1542,7 +1684,7 @@
+@@ -1542,7 +1697,7 @@
  
              if (f1 > 0.0F && target instanceof LivingEntity) {
                  entityliving = (LivingEntity) target;