Merge pull request #18441 from owncloud/ext-backends.advanced

apps/files_external/appinfo/app.php

apps/files_external/appinfo/application.php

apps/files_external/appinfo/routes.php

apps/files_external/controller/ajaxcontroller.php

apps/files_external/controller/globalstoragescontroller.php

apps/files_external/controller/storagescontroller.php

apps/files_external/controller/userstoragescontroller.php

apps/files_external/js/public_key.js

apps/files_external/lib/auth/authmechanism.php

apps/files_external/lib/auth/openstack/openstack.php

apps/files_external/lib/auth/openstack/rackspace.php

apps/files_external/lib/auth/publickey/rsa.php

apps/files_external/lib/backend/backend.php

apps/files_external/lib/backend/local.php

apps/files_external/lib/backend/sftp.php

apps/files_external/lib/backend/sftp_key.php

apps/files_external/lib/backend/smb_oc.php

apps/files_external/lib/backend/swift.php

apps/files_external/lib/permissionstrait.php

apps/files_external/lib/sftp.php