Climbing refactor (#20516)

Content.Shared/Climbing/Events/StartClimbEvent.cs

@@ -0,0 +1,7 @@
+namespace Content.Shared.Climbing.Events;
+
+/// <summary>
+///     Raised on an entity when it successfully climbs on something.
+/// </summary>
+[ByRefEvent]
+public readonly record struct StartClimbEvent(EntityUid Climbable);