Adding 2FA Authenticator Support (#66)

* Adding support for 2fa, more auth options

* WIP getting auth stuff working

* Added Manage views. 2FA working now for MVC app.

* Switching to using a controller for no-UI logout scenario

* Adding Razor Pages impl of 2FA auth stuff. Works.

src/Infrastructure/Services/EmailSender.cs

@@ -0,0 +1,16 @@
+using ApplicationCore.Interfaces;
+using System.Threading.Tasks;
+
+namespace Infrastructure.Services
+{
+    // This class is used by the application to send email for account confirmation and password reset.
+    // For more details see https://go.microsoft.com/fwlink/?LinkID=532713
+    public class EmailSender : IEmailSender
+    {
+        public Task SendEmailAsync(string email, string subject, string message)
+        {
+            // TODO: Wire this up to actual email sending logic via SendGrid, local SMTP, etc.
+            return Task.CompletedTask;
+        }
+    }
+}