feat: unique client IDs for direct server

When multiple UI applications were connecting using the same token, the actual websocket connection was getting lost, and could eventually be garbage-collected, leading to odd behavior from the UI. This is due to an existing client getting replaced and a reference to it lost. This has now been remedied, with each client getting a unique instance with a unique client ID.

src/PepperDash.Essentials.MobileControl/WebSocketServer/JoinToken.cs

@@ -0,0 +1,22 @@
+using Independentsoft.Exchange;
+
+namespace PepperDash.Essentials.WebSocketServer
+{
+  /// <summary>
+  /// Represents a join token with the associated properties
+  /// </summary>
+  public class JoinToken
+  {
+    public string Code { get; set; }
+
+    public string RoomKey { get; set; }
+
+    public string Uuid { get; set; }
+
+    public string TouchpanelKey { get; set; } = "";
+
+    public string Token { get; set; } = null;
+
+    public string Id { get; set; }
+  }
+}