Add events on animation starts (#6382)

* added AnimationStartedEvent

* added AnimationStarted event to Control

* reordered Control.AnimationStarted above Control.AnimationCompleted

* fixed comment

* switched to internal constructor and proxy method

Robust.Client/GameObjects/EntitySystems/AnimationPlayerSystem.cs

@@ -154,6 +154,9 @@ namespace Robust.Client.GameObjects
             }
 
             ent.Comp.PlayingAnimations.Add(key, playback);
+
+            var startedEvent = new AnimationStartedEvent(ent.Owner, ent.Comp, key);
+            RaiseLocalEvent(ent.Owner, startedEvent, true);
         }
 
         public bool HasRunningAnimation(EntityUid uid, string key)
@@ -199,6 +202,34 @@ namespace Robust.Client.GameObjects
         }
     }
 
+    /// <summary>
+    /// Raised whenever an animation started playing.
+    /// </summary>
+    public sealed class AnimationStartedEvent : EntityEventArgs
+    {
+        /// <summary>
+        /// The entity associated with the event.
+        /// </summary>
+        public EntityUid Uid { get; init; }
+
+        /// <summary>
+        /// The animation player component associated with the entity this event was raised on.
+        /// </summary>
+        public AnimationPlayerComponent AnimationPlayer { get; init; }
+
+        /// <summary>
+        /// The key associated with the animation that was started.
+        /// </summary>
+        public string Key { get; init; } = string.Empty;
+
+        internal AnimationStartedEvent(EntityUid uid, AnimationPlayerComponent animationPlayer, string key)
+        {
+            Uid = uid;
+            AnimationPlayer = animationPlayer;
+            Key = key;
+        }
+    }
+
     /// <summary>
     /// Raised whenever an animation stops, either due to running its course or being stopped manually.
     /// </summary>

Robust.Client/UserInterface/Control.Animations.cs

@@ -12,6 +12,7 @@ namespace Robust.Client.UserInterface
     {
         private Dictionary<string, AnimationPlayback>? _playingAnimations;
 
+        public Action<string>? AnimationStarted;
         public Action<string>? AnimationCompleted;
 
         /// <summary>
@@ -27,6 +28,7 @@ namespace Robust.Client.UserInterface
 
             _playingAnimations ??= new Dictionary<string, AnimationPlayback>();
             _playingAnimations.Add(key, playback);
+            AnimationStarted?.Invoke(key);
         }
 
         public bool HasRunningAnimation(string key)