5 new triggers: EmptyContainers, Knockdown, Stun, TriggerOnThrowDoHit (#41472)

* ideas

* finish components

* systems

* one more

* requested

---------

Co-authored-by: iaada <iaada@users.noreply.github.com>

Content.Shared/Trigger/Systems/StunOnTriggerSystem.cs

@@ -0,0 +1,17 @@
+using Content.Shared.Stunnable;
+using Content.Shared.Trigger.Components.Effects;
+
+namespace Content.Shared.Trigger.Systems;
+
+public sealed class StunOnTriggerSystem : XOnTriggerSystem<StunOnTriggerComponent>
+{
+    [Dependency] private readonly SharedStunSystem _stun = default!;
+
+    protected override void OnTrigger(Entity<StunOnTriggerComponent> ent, EntityUid target, ref TriggerEvent args)
+    {
+        if (ent.Comp.Refresh)
+            args.Handled |= _stun.TryUpdateStunDuration(target, ent.Comp.StunAmount);
+        else
+            args.Handled |= _stun.TryAddStunDuration(target, ent.Comp.StunAmount);
+    }
+}