Add opt-in for controlling what form elements are rendered via civictheme system

web/modules/custom/civictheme_dev/civictheme_dev.module

@@ -39,10 +39,6 @@ function civictheme_dev_preprocess_html(array &$variables): void {
  * Implements hook_styleguide_alter().
  */
 function civictheme_dev_styleguide_alter(array &$items): void {
-  // Remove password_confirm field from the form as CivicTheme does not support
-  // it.
-  unset($items['form']['content']['password_confirm']);
-
   _civictheme_dev_styleguide__form_test__textfield($items);
   _civictheme_dev_styleguide__form_test__textarea($items);
   _civictheme_dev_styleguide__form_test__select($items);

web/modules/custom/civictheme_dev/civictheme_dev.routing.yml

@@ -0,0 +1,14 @@
+civictheme_dev.styleguide_form:
+  path: '/civictheme-core-form-elements'
+  defaults:
+    _form: 'Drupal\civictheme_dev\Form\CoreFormElementsForm'
+    _title: 'CivicTheme Core Form Elements Form'
+  requirements:
+    _permission: 'access content'
+civictheme_dev.admin_styleguide_form:
+  path: '/admin/structure/civictheme-core-form-elements'
+  defaults:
+    _form: 'Drupal\civictheme_dev\Form\CoreFormElementsForm'
+    _title: 'Core Form Elements Form (Admin Theme)'
+  requirements:
+    _permission: 'view the administration theme'