adding hidden basic asp.net core backend (#30)

Base functionality:

    DB
    email sending
    user registration & login
    storing new characters and reading them back

Notes:

    Functionality is "hidden" with no links pointing to it.
    Most pages are scaffolded and not reviewed at all :(
    local Dev db setup is pushed to git
    NO local email setup :(

Kemkas.Web/Areas/Identity/Pages/Account/Logout.cshtml.cs

@@ -0,0 +1,43 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+#nullable disable
+
+using System;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authorization;
+using Kemkas.Web.Db.Models;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.Extensions.Logging;
+
+namespace Kemkas.Web.Areas.Identity.Pages.Account
+{
+    public class LogoutModel : PageModel
+    {
+        private readonly SignInManager<ApplicationUser> _signInManager;
+        private readonly ILogger<LogoutModel> _logger;
+
+        public LogoutModel(SignInManager<ApplicationUser> signInManager, ILogger<LogoutModel> logger)
+        {
+            _signInManager = signInManager;
+            _logger = logger;
+        }
+
+        public async Task<IActionResult> OnPost(string returnUrl = null)
+        {
+            await _signInManager.SignOutAsync();
+            _logger.LogInformation("User logged out.");
+            if (returnUrl != null)
+            {
+                return LocalRedirect(returnUrl);
+            }
+            else
+            {
+                // This needs to be a redirect so that the browser performs a new
+                // request and the identity for the user gets updated.
+                return RedirectToPage();
+            }
+        }
+    }
+}