Support archive files in file import
Support .tar.gz and .zip archives, using tarfile and zipfile. The archives should be extracted, then each of their files should be treated as if they were separate DataFiles and imported.
Bonus:
- Add
zstandardand support.tar.zstjust so we can throw artifacts at the file import. - Add support for the MIME types specific to
.tar.bz2and.tar.xz, just becausetarfilesupports them natively.
If #158 (closed) is implemented, a ZIP archive should be treated as a Transkribus import if it contains a mets.xml file, and otherwise be extracted. Other file types should not get this special treatment.