Rework startup topic handling and reenable output to logging framework (#14243)

Jellyfin.Server/ServerSetupApp/StartupLogTopic.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.ObjectModel;
+using Microsoft.Extensions.Logging;
+
+namespace Jellyfin.Server.ServerSetupApp;
+
+/// <summary>
+/// Defines a topic for the Startup UI.
+/// </summary>
+public class StartupLogTopic
+{
+    /// <summary>
+    /// Gets or Sets the LogLevel.
+    /// </summary>
+    public LogLevel LogLevel { get; set; }
+
+    /// <summary>
+    /// Gets or Sets the descriptor for the topic.
+    /// </summary>
+    public string? Content { get; set; }
+
+    /// <summary>
+    /// Gets or sets the time the topic was created.
+    /// </summary>
+    public DateTimeOffset DateOfCreation { get; set; }
+
+    /// <summary>
+    /// Gets the child items of this topic.
+    /// </summary>
+    public Collection<StartupLogTopic> Children { get; } = [];
+}