Implement enum attributes to set display order

osu.Game/Online/API/Requests/SearchBeatmapSetsRequest.cs

@@ -1,6 +1,7 @@
 // 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 System;
 using System.ComponentModel;
 using osu.Framework.IO.Network;
 using osu.Game.Overlays;
@@ -92,19 +93,59 @@ namespace osu.Game.Online.API.Requests
         Electronic = 10
     }
 
+    [HasOrderedElements]
     public enum BeatmapSearchLanguage
     {
+        [Order(0)]
         Any,
+
+        [Order(11)]
         Other,
+
+        [Order(1)]
         English,
+
+        [Order(6)]
         Japanese,
+
+        [Order(2)]
         Chinese,
+
+        [Order(10)]
         Instrumental,
+
+        [Order(7)]
         Korean,
+
+        [Order(3)]
         French,
+
+        [Order(4)]
         German,
+
+        [Order(9)]
         Swedish,
+
+        [Order(8)]
         Spanish,
+
+        [Order(5)]
         Italian
     }
+
+    [AttributeUsage(AttributeTargets.Field)]
+    public class OrderAttribute : Attribute
+    {
+        public readonly int Order;
+
+        public OrderAttribute(int order)
+        {
+            Order = order;
+        }
+    }
+
+    [AttributeUsage(AttributeTargets.Enum)]
+    public class HasOrderedElementsAttribute : Attribute
+    {
+    }
 }