Add project files.

Models/AppConfig.cs

@@ -0,0 +1,19 @@
+// This Source Code Form is subject to the terms of the MIT License.
+// If a copy of the MIT was not distributed with this file, You can obtain one at https://opensource.org/licenses/MIT.
+// Copyright (C) Leszek Pomianowski and WPF UI Contributors.
+// All Rights Reserved.
+
+namespace DownloadManager.Models;
+
+public class AppConfig
+{
+    public string ConfigurationsFolder
+    {
+        get; set;
+    }
+
+    public string AppPropertiesFileName
+    {
+        get; set;
+    }
+}