Move code from the ECA module
The namespace changes from Drupal\eca\Plugin\ECA\Modeller to Drupal\modeler_api\Plugin.
The spelling of the interface changes from ModellerInterface to ModelerInterface.
Closes #3513173
The namespace changes from Drupal\eca\Plugin\ECA\Modeller to Drupal\modeler_api\Plugin.
The spelling of the interface changes from ModellerInterface to ModelerInterface.
Closes #3513173