Move gameplay configuration to interface to allow editor overriding

osu.Game/Configuration/IGameplaySettings.cs

@@ -0,0 +1,23 @@
+// 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.
+
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+
+namespace osu.Game.Configuration
+{
+    /// <summary>
+    /// A settings provider which generally sources from <see cref="OsuConfigManager"/> (global user settings)
+    /// but can allow overriding settings by caching more locally. For instance, in the editor.
+    /// </summary>
+    /// <remarks>
+    /// More settings can be moved into this interface as required.
+    /// </remarks>
+    [Cached]
+    public interface IGameplaySettings
+    {
+        IBindable<float> ComboColourNormalisationAmount { get; }
+
+        IBindable<float> PositionalHitsoundsLevel { get; }
+    }
+}