Add an easy and reliable kill-switch for ECA
Problem/Motivation
It may happen, that a model in a Drupal site completely renders that site unusable and not even Drush commands or other ways to delete or disable such a broken config entity. To resolve such a situation, we should provide a kill-switch as a last resort, which can be used easily by (almost) anybody.
Proposed resolution
With a manual setting like $settings["eca_disable"] = TRUE; in the settings.php file, we could allow to check for that in our base event subscriber and only call the processor's execute method, when this is not set or set to FALSE. Checking for that variable is cheap and therefore acceptable when called for every subscribed event.
Edited by drupalbot