Reorganise API requests and response classes

They were previously breaking the two-class-per-file rule.

osu.Game/Online/API/Requests/Responses/APIRecentActivity.cs

@@ -0,0 +1,89 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using Humanizer;
+using Newtonsoft.Json;
+using osu.Game.Rulesets.Scoring;
+
+namespace osu.Game.Online.API.Requests.Responses
+{
+    public class APIRecentActivity
+    {
+        [JsonProperty("id")]
+        public int ID;
+
+        [JsonProperty("createdAt")]
+        public DateTimeOffset CreatedAt;
+
+        [JsonProperty]
+        private string type
+        {
+            set => Type = (RecentActivityType)Enum.Parse(typeof(RecentActivityType), value.Pascalize());
+        }
+
+        public RecentActivityType Type;
+
+        [JsonProperty]
+        private string scoreRank
+        {
+            set => ScoreRank = (ScoreRank)Enum.Parse(typeof(ScoreRank), value);
+        }
+
+        public ScoreRank ScoreRank;
+
+        [JsonProperty("rank")]
+        public int Rank;
+
+        [JsonProperty("approval")]
+        public BeatmapApproval Approval;
+
+        [JsonProperty("count")]
+        public int Count;
+
+        [JsonProperty("mode")]
+        public string Mode;
+
+        [JsonProperty("beatmap")]
+        public RecentActivityBeatmap Beatmap;
+
+        [JsonProperty("beatmapset")]
+        public RecentActivityBeatmap Beatmapset;
+
+        [JsonProperty("user")]
+        public RecentActivityUser User;
+
+        [JsonProperty("achievement")]
+        public RecentActivityAchievement Achievement;
+
+        public class RecentActivityBeatmap
+        {
+            [JsonProperty("title")]
+            public string Title;
+
+            [JsonProperty("url")]
+            public string Url;
+        }
+
+        public class RecentActivityUser
+        {
+            [JsonProperty("username")]
+            public string Username;
+
+            [JsonProperty("url")]
+            public string Url;
+
+            [JsonProperty("previousUsername")]
+            public string PreviousUsername;
+        }
+
+        public class RecentActivityAchievement
+        {
+            [JsonProperty("slug")]
+            public string Slug;
+
+            [JsonProperty("name")]
+            public string Name;
+        }
+    }
+}