[Registry Preview] Adds application to Open with list for REG files (#26033)

* 25834

* Asociate Registry Preview with .reg files

* Add setting for making RP default app for .reg files

* Run spellcheck

* Run spellcheck again

* Fix build

---------

Co-authored-by: Stefan Markovic <stefan@janeasystems.com>

src/settings-ui/Settings.UI.Library/SndRegistryPreviewSettings.cs

@@ -0,0 +1,29 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Microsoft.PowerToys.Settings.UI.Library
+{
+    public class SndRegistryPreviewSettings
+    {
+        [JsonPropertyName("RegistryPreview")]
+        public RegistryPreviewSettings RegistryPreview { get; set; }
+
+        public SndRegistryPreviewSettings()
+        {
+        }
+
+        public SndRegistryPreviewSettings(RegistryPreviewSettings settings)
+        {
+            RegistryPreview = settings;
+        }
+
+        public string ToJsonString()
+        {
+            return JsonSerializer.Serialize(this);
+        }
+    }
+}