added support for Forgot Username and Use Login Link

Oqtane.Server/Pages/LoginLink.cshtml

@@ -0,0 +1,3 @@
+@page "/pages/loginlink"
+@namespace  Oqtane.Pages
+@model Oqtane.Pages.LoginLinkModel

Oqtane.Server/Pages/LoginLink.cshtml.cs

@@ -0,0 +1,69 @@
+using System;
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Oqtane.Enums;
+using Oqtane.Extensions;
+using Oqtane.Infrastructure;
+using Oqtane.Managers;
+using Oqtane.Shared;
+
+namespace Oqtane.Pages
+{
+    [AllowAnonymous]
+    public class LoginLinkModel : PageModel
+    {
+        private readonly UserManager<IdentityUser> _identityUserManager;
+        private readonly SignInManager<IdentityUser> _identitySignInManager;
+        private readonly IUserManager _userManager;
+        private readonly ILogManager _logger;
+
+        public LoginLinkModel(UserManager<IdentityUser> identityUserManager, SignInManager<IdentityUser> identitySignInManager, IUserManager userManager, ILogManager logger)
+        {
+            _identityUserManager = identityUserManager;
+            _identitySignInManager = identitySignInManager;
+            _userManager = userManager;
+            _logger = logger;
+        }
+
+        public async Task<IActionResult> OnGetAsync(string name, string token)
+        {
+            var returnurl = "/login";
+
+            if (bool.Parse(HttpContext.GetSiteSettings().GetValue("LoginOptions:LoginLink", "false")) &&
+                !User.Identity.IsAuthenticated && !string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(token))
+            {
+                var validuser = false;
+
+                IdentityUser identityuser = await _identityUserManager.FindByNameAsync(name);
+                if (identityuser != null)
+                {
+                    var user = _userManager.GetUser(identityuser.UserName, HttpContext.GetAlias().SiteId);
+                    if (user != null && user.TwoFactorCode == token && DateTime.UtcNow < user.TwoFactorExpiry)
+                    {
+                        await _identitySignInManager.SignInAsync(identityuser, false);
+                        _logger.Log(LogLevel.Information, this, LogFunction.Security, "Login Link Successful For User {Username}", name);
+                        validuser = true;
+                        returnurl = "/";
+                    }
+                }
+
+                if (!validuser)
+                {
+                    _logger.Log(LogLevel.Error, this, LogFunction.Security, "Login Link Failed For User {Username}", name);
+                    returnurl += $"?status={ExternalLoginStatus.LoginLinkFailed}";
+                }
+            }
+            else
+            {
+                _logger.Log(LogLevel.Error, this, LogFunction.Security, "Unauthorized Login Link Attempt For User {Username}", name);
+                returnurl = "/";
+            }
+
+            return LocalRedirect(Url.Content("~" + returnurl));
+        }
+    }
+}