Merge pull request #21288 from owncloud/deprecated_helper_mimetypes

apps/dav/lib/connector/sabre/file.php

apps/files/download.php

apps/files/lib/helper.php

apps/files_sharing/templates/public.php

apps/files_versions/download.php

lib/private/helper.php

lib/private/preview.php

lib/private/template/functions.php

tests/lib/helper.php