Move `pyzip` utility from pyodide-build to pyodide/pyodide

[ryanking13]

Description

The pyodide-build repository contains a utility for creating a Python zipfile from a directory. This functionality is used exclusively by the pyodide/pyodide repository to bundle the Python standard library, which the Pyodide runtime then loads using zipimport. (code pointer

This issue proposes migrating the utility from pyodide-build to the main Pyodide repository.

Why

The pyodide-build repository's primary purpose is to build packages for Pyodide. The pyzip utility, however, is used only for the core Pyodide runtime build and has no connection to the package build process.

Current state

The pyodide-build repository includes a feature to create a zipfile of Python scripts, implemented in:

• pyodide_build/pyzip.py
• pyodide_build/cli/create_zipfile.py

What to do

I think we can refactor it to a single script, put it under the tools directory inside Pyodide repository.