Resolve "Zip archives that do not just have a folder as top level entity are treated incorrectly"

Closes #150 (closed)

• Exception is raised on unsupported archive structures
• unit test added to test support of different structures

REMARK: In Issue description was mentioned, that unclear whether to raise errors or try to recover. Since I'm not aware which other kind of structures are likely to appear, I decided to throw a Exception whenever an archive does not match the needed structure. With additional information of likely appearing other structure I can add custom error handling / recovering, but without it, it does not make sense to handle unknown structures in my eyes.

UPDATE: Fails Pipeline, because uautomator not fulfills pythons zipfile structure conventions, see (https://docs.python.org/3/library/zipfile.html#zipfile.ZipInfo.is_dir)