Add tiered level badge colouring

osu.Game/Scoring/RankingTier.cs

@@ -0,0 +1,17 @@
+// 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.Scoring
+{
+    public enum RankingTier
+    {
+        Iron,
+        Bronze,
+        Silver,
+        Gold,
+        Platinum,
+        Rhodium,
+        Radiant,
+        Lustrous
+    }
+}