Add all websocket messages to generated openapi spec (#9682)

* Add all websocket messages to generated openapi spec

* Use oneOf

* JsonIgnore ServerId

* Oops

* Add discriminators

* Add WebSocketMessage container for Inbound and Outbound messages

MediaBrowser.Controller/Net/WebSocketMessages/Outbound/SessionsMessage.cs

@@ -0,0 +1,24 @@
+using System.ComponentModel;
+using MediaBrowser.Controller.Session;
+using MediaBrowser.Model.Session;
+
+namespace MediaBrowser.Controller.Net.WebSocketMessages.Outbound;
+
+/// <summary>
+/// Sessions message.
+/// </summary>
+public class SessionsMessage : WebSocketMessage<SessionInfo>, IOutboundWebSocketMessage
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SessionsMessage"/> class.
+    /// </summary>
+    /// <param name="data">Session info.</param>
+    public SessionsMessage(SessionInfo data)
+        : base(data)
+    {
+    }
+
+    /// <inheritdoc />
+    [DefaultValue(SessionMessageType.Sessions)]
+    public override SessionMessageType MessageType => SessionMessageType.Sessions;
+}