Added scaffolded Login page for Identity

- Also updated the _LoginPartial to use the new page

src/Web/Areas/Identity/Pages/Account/Login.cshtml

@@ -0,0 +1,63 @@
+@page
+@model LoginModel
+
+@{
+    ViewData["Title"] = "Log in";
+}
+
+<h2>@ViewData["Title"]</h2>
+<div class="container" account-login-container>
+    <div class="row">
+        <div class="col-md-12">
+            <section>
+                <form method="post">
+                    <h4>Use a local account to log in.</h4>
+                    <hr />
+                    <div asp-validation-summary="All" class="text-danger"></div>
+                    <div class="form-group">
+                        <label asp-for="Input.Email"></label>
+                        <input asp-for="Input.Email" class="form-control" />
+                        <span asp-validation-for="Input.Email" class="text-danger"></span>
+                    </div>
+                    <div class="form-group">
+                        <label asp-for="Input.Password"></label>
+                        <input asp-for="Input.Password" class="form-control" />
+                        <span asp-validation-for="Input.Password" class="text-danger"></span>
+                    </div>
+                    <div class="form-group">
+                        <div class="checkbox">
+                            <label asp-for="Input.RememberMe">
+                                <input asp-for="Input.RememberMe" />
+                                @Html.DisplayNameFor(m => m.Input.RememberMe)
+                            </label>
+                        </div>
+                    </div>
+                    <div class="form-group">
+                        <button type="submit" class="btn btn-default">Log in</button>
+                    </div>
+                    <div class="form-group">
+                        <p>
+                            <a asp-page="./ForgotPassword">Forgot your password?</a>
+                        </p>
+                        <p>
+                            <a asp-page="./Register" asp-route-returnUrl="@Model.ReturnUrl">Register as a new user</a>
+                        </p>
+                    </div>
+                    <p>
+                        Note that for demo purposes you don't need to register and can login with these credentials:
+                    </p>
+                    <p>
+                        User:     <b>demouser@microsoft.com</b>
+                    </p>
+                    <p>
+                        Password: <b>Pass@word1</b>
+                    </p>
+                </form>
+            </section>
+        </div>
+    </div>
+</div>
+
+@section Scripts {
+    <partial name="_ValidationScriptsPartial" />
+}

src/Web/Areas/Identity/Pages/Account/Login.cshtml.cs

@@ -0,0 +1,103 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.eShopWeb.Infrastructure.Identity;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.eShopWeb.Web.Areas.Identity.Pages.Account
+{
+    [AllowAnonymous]
+    public class LoginModel : PageModel
+    {
+        private readonly SignInManager<ApplicationUser> _signInManager;
+        private readonly ILogger<LoginModel> _logger;
+
+        public LoginModel(SignInManager<ApplicationUser> signInManager, ILogger<LoginModel> logger)
+        {
+            _signInManager = signInManager;
+            _logger = logger;
+        }
+
+        [BindProperty]
+        public InputModel Input { get; set; }
+
+        public IList<AuthenticationScheme> ExternalLogins { get; set; }
+
+        public string ReturnUrl { get; set; }
+
+        [TempData]
+        public string ErrorMessage { get; set; }
+
+        public class InputModel
+        {
+            [Required]
+            [EmailAddress]
+            public string Email { get; set; }
+
+            [Required]
+            [DataType(DataType.Password)]
+            public string Password { get; set; }
+
+            [Display(Name = "Remember me?")]
+            public bool RememberMe { get; set; }
+        }
+
+        public async Task OnGetAsync(string returnUrl = null)
+        {
+            if (!string.IsNullOrEmpty(ErrorMessage))
+            {
+                ModelState.AddModelError(string.Empty, ErrorMessage);
+            }
+
+            returnUrl = returnUrl ?? Url.Content("~/");
+
+            // Clear the existing external cookie to ensure a clean login process
+            await HttpContext.SignOutAsync(IdentityConstants.ExternalScheme);
+
+            ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();
+
+            ReturnUrl = returnUrl;
+        }
+
+        public async Task<IActionResult> OnPostAsync(string returnUrl = null)
+        {
+            returnUrl = returnUrl ?? Url.Content("~/");
+
+            if (ModelState.IsValid)
+            {
+                // This doesn't count login failures towards account lockout
+                // To enable password failures to trigger account lockout, set lockoutOnFailure: true
+                var result = await _signInManager.PasswordSignInAsync(Input.Email, Input.Password, Input.RememberMe, lockoutOnFailure: true);
+                if (result.Succeeded)
+                {
+                    _logger.LogInformation("User logged in.");
+                    return LocalRedirect(returnUrl);
+                }
+                if (result.RequiresTwoFactor)
+                {
+                    return RedirectToPage("./LoginWith2fa", new { ReturnUrl = returnUrl, RememberMe = Input.RememberMe });
+                }
+                if (result.IsLockedOut)
+                {
+                    _logger.LogWarning("User account locked out.");
+                    return RedirectToPage("./Lockout");
+                }
+                else
+                {
+                    ModelState.AddModelError(string.Empty, "Invalid login attempt.");
+                    return Page();
+                }
+            }
+
+            // If we got this far, something failed, redisplay form
+            return Page();
+        }
+    }
+}

src/Web/Areas/Identity/Pages/Account/_ViewImports.cshtml

@@ -0,0 +1 @@
+@using Microsoft.eShopWeb.Web.Areas.Identity.Pages.Account