Add config to limit concurrent logins (#14967)

* Add new config options

* Change validation interval + related changes

* Fix typo

* Temp fix

* Set new setting to false for new dotnet projects

* Added logic to update security stamp on sign in + fixed wierd code calling handle signIn twice

* Cleanup

* Adding empty ctors

---------

Co-authored-by: Elitsa <elm@umbraco.dk>

templates/UmbracoProject/appsettings.json

@@ -36,6 +36,9 @@
       },
       "Unattended": {
         "UpgradeUnattended": true
+      },
+      "Security": {
+        "AllowConcurrentLogins": false
       }
     }
   }