Add package_type field to repodata.json. ### Description

This PR adds `package_type` field to repodata.json and use it to create a list of unvendored standard libraries. After this we don't need to manage a hard-coded list of unvendored stdlib lists in pyodide-py.

### Checklists

- [x] Add / update tests

package:
  name: pycryptodome
  version: 3.16.0
  top-level:
    - Crypto
source:
  url: https://files.pythonhosted.org/packages/0d/66/5e4a14e91ffeac819e6888037771286bc1b86869f25d74d60bc4a61d2c1e/pycryptodome-3.16.0.tar.gz
  sha256: 0e45d2d852a66ecfb904f090c3f87dc0dfb89a499570abad8590f10d9cffb350
build:
  exports: requested
about:
  home: https://www.pycryptodome.org
  PyPI: https://pypi.org/project/pycryptodome
  summary: Cryptographic library for Python
  license: BSD, Public Domain

package:
  name: pycryptodome
  version: 3.16.0
  top-level:
    - Crypto
source:
  url: https://files.pythonhosted.org/packages/0d/66/5e4a14e91ffeac819e6888037771286bc1b86869f25d74d60bc4a61d2c1e/pycryptodome-3.16.0.tar.gz
  sha256: 0e45d2d852a66ecfb904f090c3f87dc0dfb89a499570abad8590f10d9cffb350
build:
  exports: requested
about:
  home: https://www.pycryptodome.org
  PyPI: https://pypi.org/project/pycryptodome
  summary: Cryptographic library for Python
  license: BSD, Public Domain
