2021-08-27-added-import-export-log-cleanup-task.md

title	issue	author	author_email	author_github
Added import export log cleanup task	NEXT-11765	d.neustadt	d.neustadt@shopware.com	dneustadt

Core

• Added CleanupImportExportLogTask and CleanupImportExportLogTaskHandler
• Changed FileDeletedSubscriber to fix files not being deleted in filesystem on deletion of ImportExportFileEntity entities
• Added CascadeDelete flag to log property of ImportExportFileDefinition and updated the according foreign key of table import_export_log to delete corrensponding logs when expired import_export_file entries are deleted