Add lava (#13438)

Content.Shared/Throwing/LandEvent.cs

@@ -5,11 +5,8 @@ namespace Content.Shared.Throwing
     /// <summary>
     ///     Raised when an entity that was thrown lands. This occurs before they stop moving and is when their tile-friction is reapplied.
     /// </summary>
-    [PublicAPI]
-    public sealed class LandEvent : EntityEventArgs
-    {
-        public EntityUid? User;
-    }
+    [ByRefEvent]
+    public readonly record struct LandEvent(EntityUid? User);
 
     /// <summary>
     /// Raised when a thrown entity is no longer moving.