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

from pytest_pyodide import run_in_pyodide


@run_in_pyodide(
    packages=[
        "rebound",
        "numpy",
    ]
)
def test_integrate(selenium):
    import numpy
    import rebound

    sim = rebound.Simulation()
    sim.add(m=1)
    sim.add(m=1e-3, a=1)
    sim.add(m=1e-3, a=2)
    sim.integrate(10)

    assert numpy.fabs(sim.t - 10.0) < 1e-10, "Orbit integration not working"
    return None

from pytest_pyodide import run_in_pyodide


@run_in_pyodide(
    packages=[
        "rebound",
        "numpy",
    ]
)
def test_integrate(selenium):
    import numpy
    import rebound

    sim = rebound.Simulation()
    sim.add(m=1)
    sim.add(m=1e-3, a=1)
    sim.add(m=1e-3, a=2)
    sim.integrate(10)

    assert numpy.fabs(sim.t - 10.0) < 1e-10, "Orbit integration not working"
    return None
