Clean up owned playerinfo's when disconnecting

This commit does what official servers do:
- despawn the PlayerInfo if someone disconnects while in the lobby
- despawn all PlayerInfos at the end of a game when the EndGame screen
is shown. At this point a lot of other netobjects are destroyed as well,
with the PlayerInfos generally done first.

src/Impostor.Server/Net/State/Game.Data.cs

@@ -510,6 +510,18 @@ namespace Impostor.Server.Net.State
             await SendObjectSpawnAsync(playerInfo);
         }
 
+        private async ValueTask DespawnPlayerInfoAsync(InnerPlayerInfo playerInfo)
+        {
+            if (playerInfo.OwnerId == ServerOwned)
+            {
+                _logger.LogDebug("Despawning PlayerInfo {nid}", playerInfo.NetId);
+                GameNet.GameData.RemovePlayer(playerInfo.PlayerId);
+                RemoveNetObject(playerInfo);
+
+                await SendObjectDespawnAsync(playerInfo);
+            }
+        }
+
         private bool AddNetObject(InnerNetObject obj)
         {
             if (_allObjectsFast.ContainsKey(obj.NetId))

src/Impostor.Server/Net/State/Game.Incoming.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Impostor.Api.Games;
@@ -43,6 +44,12 @@ namespace Impostor.Server.Net.State
                 player.Value.Limbo = LimboStates.PreSpawn;
             }
 
+            // Delete all PlayerInfo objects
+            foreach (var playerInfo in GameNet.GameData.Players.Values.ToList())
+            {
+                await DespawnPlayerInfoAsync(playerInfo);
+            }
+
             await _eventManager.CallAsync(new GameEndedEvent(this, gameOverReason));
         }
 

src/Impostor.Server/Net/State/Game.Outgoing.cs

@@ -134,5 +134,14 @@ namespace Impostor.Server.Net.State
             writer.EndMessage();
             await FinishGameDataAsync(writer, targetClientId);
         }
+
+        private ValueTask SendObjectDespawnAsync(InnerNetObject obj, int? targetClientId = null)
+        {
+            using var writer = StartGameData(targetClientId);
+            writer.StartMessage(GameDataTag.DespawnFlag);
+            writer.WritePacked(obj.NetId);
+            writer.EndMessage();
+            return FinishGameDataAsync(writer, targetClientId);
+        }
     }
 }

src/Impostor.Server/Net/State/Game.State.cs

@@ -85,6 +85,13 @@ namespace Impostor.Server.Net.State
                 }
             });
 
+            // Clean up the PlayerInfo if we own it and we're still in the lobby
+            if (GameState == GameStates.NotStarted)
+            {
+                var playerInfo = GameNet.GameData.PlayersByClientId[playerId];
+                await DespawnPlayerInfoAsync(playerInfo);
+            }
+
             return true;
         }