Add chapter 10 sample project

Chapter10/TemplateStudioSampleApp/Helpers/ResourceExtensions.cs

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+using Microsoft.Windows.ApplicationModel.Resources;
+
+namespace TemplateStudioSampleApp.Helpers;
+
+public static class ResourceExtensions
+{
+    private static readonly ResourceLoader _resourceLoader = new();
+
+    public static string GetLocalized(this string resourceKey) => _resourceLoader.GetString(resourceKey);
+}