Convert config_test_add_page() to a new style controller

The patch to convert this to a controller.

+++ b/core/modules/config/tests/config_test/config_test.routing.ymlundefined
@@ -0,0 +1,6 @@
+    _content: '\Drupal\config_test\Controller\ConfigTestController::addConfigTest'

You should be able to just have _entity_form: 'config_test', and then you can ditch the whole ConfigTestController

Changed it and it seems to work fine.

Removed the controller, changed the routing file to _entity_form.

He, making progress by basically just removing code. Tests are running fine, so this feels great.

Needs reroll...

curl https://drupal.org/files/drupal-convert_config_test_add_page-1987662-3.patch | git a
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  1602  100  1602    0     0  17189      0 --:--:-- --:--:-- --:--:-- 20538
error: core/modules/config/tests/config_test/config_test.routing.yml: already exists in index

I'll help!

Rerolled!

No interdiff because the old patch didn't apply. Also, it's literally just a re-roll.

Thanks!

#1987668: Convert config_test module to routes I am sorry for doing this.