Update Razor page template to use file-scoped namespaces

#33947

Author: DamianEdwards

src/ProjectTemplates/Web.ItemTemplates/content/RazorPage/Index.cshtml.cs

@@ -5,16 +5,15 @@
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.RazorPages;
 
-namespace MyApp.Namespace
-{
+namespace MyApp.Namespace;
+
 #if NameIsPage
-    public class IndexModel : Microsoft.AspNetCore.Mvc.RazorPages.PageModel
+public class IndexModel : Microsoft.AspNetCore.Mvc.RazorPages.PageModel
 #else
-    public class IndexModel : PageModel
+public class IndexModel : PageModel
 #endif
+{
+    public void OnGet()
     {
-        public void OnGet()
-        {
-        }
     }
 }