Adding ckeditor_a11ychecker

Author: stankut

composer.json

@@ -87,6 +87,7 @@
         "composer/installers": "^1.9",
         "cweagans/composer-patches": "^1.7",
         "drupal/bootstrap": "^3.21",
+        "drupal/ckeditor_a11ychecker": "^3.0",
         "drupal/coc_forms_auto_export": "^2.0@alpha",
         "drupal/color": "^1.0",
         "drupal/core-composer-scaffold": "^10",