add census popup on connection

MareSynchronos/Services/Mediator/Messages.cs

@@ -72,6 +72,7 @@ public record PairHandlerVisibleMessage(PairHandler Player) : MessageBase;
 public record RefreshUiMessage : MessageBase;
 public record OpenReportPopupMessage(Pair PairToReport) : MessageBase;
 public record OpenBanUserPopupMessage(Pair PairToBan, GroupFullInfoDto GroupFullInfoDto) : MessageBase;
+public record OpenCensusPopupMessage() : MessageBase;
 public record OpenSyncshellAdminPanel(GroupFullInfoDto GroupInfo) : MessageBase;
 public record OpenPermissionWindow(Pair Pair) : MessageBase;
 public record DownloadLimitChangedMessage() : SameThreadMessage;

MareSynchronos/Services/ServerConfiguration/ServerConfigurationManager.cs

@@ -44,6 +44,19 @@ public class ServerConfigurationManager
         }
     }
 
+    public bool ShownCensusPopup
+    {
+        get
+        {
+            return _configService.Current.ShownCensusPopup;
+        }
+        set
+        {
+            _configService.Current.ShownCensusPopup = value;
+            _configService.Save();
+        }
+    }
+
     public int CurrentServerIndex
     {
         set