archive/zip: fix reading, writing of zip64 archives
Read zip files that contain only 64-bit header offset, not 64-bit sizes.
Fixes #13367.
Read zip files that contain completely unexpected Extra fields,
provided we do not need to find 64-bit size or header offset information there.
Fixes #13166.
Write zip file entries with 0xFFFFFFFF uncompressed data bytes
correctly (must use zip64 header, since that's the magic indicator).
Fixes new TestZip64EdgeCase. (Noticed while working on the CL.)