Add datafiles package type #4892

🚀 Feature

A package type that just unzips to a given directory on the pyodide filesystem (optionally overwriting directories if they exist)

Motivation

In #4889 I add a package that lets you install the unix timezone database to the right place on your pyodide runtime. You have to import the python package which then copies the timezone data to the right place. It would be nicer to have a way to add a package to pyodide that just installed the files directly to where I want them on the filesystem (/usr/share/zoneinfo)

Alternatives

The alternative is to do it via a python module, as I do in #4889 but this means patching any modules that need it as a dependency to make sure the import the module which is a pain.

Additional context

I hit this in building Apache Arrow - it requires the timezone database to be in the same format and in the place it lives on unix systems, and Arrow maintainers don't want to embed tz data into the Python wheel.