Add Support for Zip64 Data Descriptor

[harrismcc]

Zip64 compressed zips with the file size in the data descriptor (after the file data) are currently not supported. The pipeline needs to be reworked slightly to make this possible.

[harrismcc]

I think the path forward with this is that, instead of pre-calculating the file size and using slice we scan the current chunk for the next bit flag. If found, we know the length and can proceed. If not found, then we must still be in the file data so just pass along the whole chunk and move on.

^ Note this is just for cases where the file length is unknown. If we know the length then ReadingNextFlag should take care of the data descriptor