Changes to List engines

the settings response's property default value changed from {} to {"use_case":"generic_ap"} for the status 200

added the optional property results/items/allOf[subschema #1: Engine object]/created_at to the response with the 200 status

added the optional property results/items/allOf[subschema #1: Engine object]/created_by to the response with the 200 status

added the optional property results/items/allOf[subschema #1: Engine object]/modified_at to the response with the 200 status

added the optional property results/items/allOf[subschema #1: Engine object]/modified_by to the response with the 200 status

the results/items response's property type changed from object to no type for status 200

removed the optional property results/items/agenda_id from the response with the 200 status

removed the optional property results/items/description from the response with the 200 status

removed the optional property results/items/id from the response with the 200 status

removed the optional property results/items/learning_enabled from the response with the 200 status

removed the optional property results/items/name from the response with the 200 status

removed the optional property results/items/organization from the response with the 200 status

removed the optional property results/items/training_queues from the response with the 200 status

removed the optional property results/items/type from the response with the 200 status

removed the optional property results/items/url from the response with the 200 status

added engine_base subschema #2 to the results/items response property allOf list for the response status 200