Refactoring authentication to support server-side Blazor using a seamless login flow.

Oqtane.Server/Pages/Logout.cshtml.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Security.Claims;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Authentication.Cookies;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Oqtane.Models;
+
+namespace Oqtane.Pages
+{
+    [IgnoreAntiforgeryToken(Order = 1001)]
+    [AllowAnonymous]
+    public class LogoutModel : PageModel
+    {
+        public async Task<IActionResult> OnPostAsync()
+        {
+            await HttpContext.SignOutAsync(IdentityConstants.ApplicationScheme);
+
+            return LocalRedirect(Url.Content("~/"));
+        }
+    }
+}