reproducible universal zip build

[illwieckz]

This thread is to track various issue about making reproducible universal zip.

Things that may prevent zip to be reproducible:

• zip metadata like file data, file time, file permission
• in which order the files are added to the zip archive
• zip recompression (I currently use advzip -r -k -4 <zip file> before distribution)

This also depends of reproducible engine zip and reproducible dpk archives:

• reproducible engine zip build #14
• reproducible dpk archive build UnvanquishedAssets/UnvanquishedAssets#6