Restructure explosion to ensure proper lifetime bounds

osu.Game.Rulesets.Catch/UI/IHitExplosion.cs

@@ -0,0 +1,16 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+namespace osu.Game.Rulesets.Catch.UI
+{
+    /// <summary>
+    /// Common interface for all hit explosion skinnables.
+    /// </summary>
+    public interface IHitExplosion
+    {
+        /// <summary>
+        /// Begins animating this <see cref="IHitExplosion"/>.
+        /// </summary>
+        void Animate(HitExplosionEntry entry);
+    }
+}