Refactors throw events, makes cream pies ECS (#4500)

Content.Server/Damage/DamageOtherOnHitSystem.cs

@@ -0,0 +1,23 @@
+using Content.Server.Damage.Components;
+using Content.Shared.Damage.Components;
+using Content.Shared.Throwing;
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.Damage
+{
+    public class DamageOtherOnHitSystem : EntitySystem
+    {
+        public override void Initialize()
+        {
+            SubscribeLocalEvent<DamageOtherOnHitComponent, ThrowDoHitEvent>(OnDoHit);
+        }
+
+        private void OnDoHit(EntityUid uid, DamageOtherOnHitComponent component, ThrowDoHitEvent args)
+        {
+            if (!args.Target.TryGetComponent(out IDamageableComponent? damageable))
+                return;
+
+            damageable.ChangeDamage(component.DamageType, component.Amount, component.IgnoreResistances, args.User);
+        }
+    }
+}