Added BitmapIconSourceExtension type

Author: Sergio0694

Microsoft.Toolkit.Uwp.UI/Extensions/Markup/BitmapIconSourceExtension.cs

@@ -0,0 +1,37 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Markup;
+
+namespace Microsoft.Toolkit.Uwp.UI.Extensions
+{
+    /// <summary>
+    /// Custom <see cref="MarkupExtension"/> which can provide <see cref="BitmapIconSource"/> values.
+    /// </summary>
+    [MarkupExtensionReturnType(ReturnType = typeof(BitmapIconSource))]
+    public sealed class BitmapIconSourceExtension : MarkupExtension
+    {
+        /// <summary>
+        /// Gets or sets the <see cref="Uri"/> representing the image to display.
+        /// </summary>
+        public Uri Source { get; set; }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether to display the icon as monochrome.
+        /// </summary>
+        public bool ShowAsMonochrome { get; set; }
+
+        /// <inheritdoc/>
+        protected override object ProvideValue()
+        {
+            return new BitmapIconSource
+            {
+                ShowAsMonochrome = ShowAsMonochrome,
+                UriSource = Source
+            };
+        }
+    }
+}