feat: add a script to pack assignment files

[aeft]

@silverbullettt Thanks for this awesome project and assignment!

I want to add a script to make the pack a little bit easier.

1. This script can generate the zip file automatically based on the assignment requirement.
2. I have tested on Mac and Ubuntu.
3. If this PR is accepted maybe we can also update the docs in https://tai-e.pascal-lab.net/lectures.html