Add HasInitialized to DHO

As it turned out, `IsLoaded` is not a reliable way.

osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs

@@ -146,6 +146,11 @@ namespace osu.Game.Rulesets.Objects.Drawables
 
         private Container<PausableSkinnableSound> samplesContainer;
 
+        /// <summary>
+        /// Whether the initialization logic in <see cref="Playfield" /> has applied.
+        /// </summary>
+        internal bool HasInitialized;
+
         /// <summary>
         /// Creates a new <see cref="DrawableHitObject"/>.
         /// </summary>