[PreviewPane][Monaco]Format json/xml before rendering (#19980)

src/modules/previewpane/MonacoPreviewHandler/Formatters/JsonFormatter.cs

@@ -0,0 +1,28 @@
+// 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.
+
+namespace Microsoft.PowerToys.PreviewHandler.Monaco.Formatters
+{
+    using System.Text.Json;
+
+    public class JsonFormatter : IFormatter
+    {
+        /// <inheritdoc/>
+        public string LangSet => "json";
+
+        /// <inheritdoc/>
+        public string Format(string value)
+        {
+            if (string.IsNullOrWhiteSpace(value))
+            {
+                return string.Empty;
+            }
+
+            using (var jDocument = JsonDocument.Parse(value, new JsonDocumentOptions { CommentHandling = JsonCommentHandling.Skip }))
+            {
+                return JsonSerializer.Serialize(jDocument, new JsonSerializerOptions { WriteIndented = true });
+            }
+        }
+    }
+}