Fix some weirdness around forced multiplayer elements

- Naming wasn't adjusted
- When the chat collapsed, the team score display broke due to zero
  width

Partial revert of
https://github.com/ppy/osu/commit/da1fc1013e07b8dafb0c409354f9d1cef971e449.

osu.Game/Screens/OnlinePlay/Multiplayer/GameplayChatDisplay.cs

@@ -38,8 +38,8 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         public GameplayChatDisplay(Room room)
             : base(room, leaveChannelOnDispose: false)
         {
+            RelativeSizeAxes = Axes.X;
             Background.Alpha = 0.2f;
-            Width = width;
         }
 
         [BackgroundDependencyLoader]

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerPlayer.cs

@@ -8,6 +8,8 @@ using System.Threading.Tasks;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Extensions.ObjectExtensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
 using osu.Framework.Logging;
 using osu.Framework.Screens;
 using osu.Game.Graphics.UserInterface;
@@ -18,6 +20,7 @@ using osu.Game.Screens.Play;
 using osu.Game.Screens.Ranking;
 using osu.Game.Screens.Select.Leaderboards;
 using osu.Game.Users;
+using osuTK;
 
 namespace osu.Game.Screens.OnlinePlay.Multiplayer
 {
@@ -70,13 +73,22 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
 
             ScoreProcessor.ApplyNewJudgementsWhenFailed = true;
 
-            LoadComponentAsync(chat = new GameplayChatDisplay(Room), HUDOverlay.LeaderboardFlow.Add);
-
-            LoadComponentAsync(teamScoreDisplay = new GameplayMatchScoreDisplay
+            LoadComponentAsync(new FillFlowContainer
             {
-                Expanded = { BindTarget = HUDOverlay.ShowHud },
-                Alpha = 0,
-            }, scoreDisplay => HUDOverlay.LeaderboardFlow.Insert(1, scoreDisplay));
+                Width = 260,
+                Direction = FillDirection.Vertical,
+                Spacing = new Vector2(5),
+                Children = new Drawable[]
+                {
+                    chat = new GameplayChatDisplay(Room),
+                    teamScoreDisplay = new GameplayMatchScoreDisplay
+                    {
+                        Expanded = { BindTarget = HUDOverlay.ShowHud },
+                        Alpha = 0,
+                    }
+                }
+            }, HUDOverlay.TopLeftElements.Add);
+
             LoadComponentAsync(leaderboardProvider, loaded =>
             {
                 AddInternal(loaded);

osu.Game/Screens/Play/HUDOverlay.cs

@@ -86,9 +86,14 @@ namespace osu.Game.Screens.Play
         private readonly BindableBool replayLoaded = new BindableBool();
 
         private static bool hasShownNotificationOnce;
-        private readonly FillFlowContainer bottomRightElements;
 
+        // The following flows are used to attach fixed non-skinnable elements in particular implementations of the player
+        // (e.g. replay or multiplayer-specific controls).
+        // They will make a best-effort attempt to get out of the way of any other skinnable components.
+
+        public readonly FillFlowContainer TopLeftElements;
         internal readonly FillFlowContainer TopRightElements;
+        private readonly FillFlowContainer bottomRightElements;
 
         internal readonly IBindable<bool> IsPlaying = new Bindable<bool>();
 
@@ -101,12 +106,6 @@ namespace osu.Game.Screens.Play
         [CanBeNull]
         private readonly SkinnableContainer rulesetComponents;
 
-        /// <summary>
-        /// A flow which sits at the left side of the screen to house leaderboard (and related) components.
-        /// Will automatically be positioned to avoid colliding with top scoring elements.
-        /// </summary>
-        public readonly FillFlowContainer LeaderboardFlow;
-
         private readonly List<Drawable> hideTargets;
 
         /// <summary>
@@ -177,7 +176,7 @@ namespace osu.Game.Screens.Play
                         PlayerSettingsOverlay = new PlayerSettingsOverlay(),
                     }
                 },
-                LeaderboardFlow = new FillFlowContainer
+                TopLeftElements = new FillFlowContainer
                 {
                     AutoSizeAxes = Axes.Both,
                     Direction = FillDirection.Vertical,
@@ -191,7 +190,7 @@ namespace osu.Game.Screens.Play
             if (rulesetComponents != null)
                 hideTargets.Add(rulesetComponents);
 
-            hideTargets.Add(LeaderboardFlow);
+            hideTargets.Add(TopLeftElements);
         }
 
         [BackgroundDependencyLoader(true)]
@@ -285,10 +284,10 @@ namespace osu.Game.Screens.Play
             else
                 TopRightElements.Y = 0;
 
-            if (lowestTopScreenSpaceLeft.HasValue && DrawHeight - LeaderboardFlow.DrawHeight > 0)
-                LeaderboardFlow.Y = Math.Clamp(ToLocalSpace(new Vector2(0, lowestTopScreenSpaceLeft.Value)).Y, 0, DrawHeight - LeaderboardFlow.DrawHeight);
+            if (lowestTopScreenSpaceLeft.HasValue && DrawHeight - TopLeftElements.DrawHeight > 0)
+                TopLeftElements.Y = Math.Clamp(ToLocalSpace(new Vector2(0, lowestTopScreenSpaceLeft.Value)).Y, 0, DrawHeight - TopLeftElements.DrawHeight);
             else
-                LeaderboardFlow.Y = 0;
+                TopLeftElements.Y = 0;
 
             if (highestBottomScreenSpace.HasValue && DrawHeight - bottomRightElements.DrawHeight > 0)
                 bottomRightElements.Y = BottomScoringElementsHeight = -Math.Clamp(DrawHeight - ToLocalSpace(highestBottomScreenSpace.Value).Y, 0, DrawHeight - bottomRightElements.DrawHeight);