This is the mirror image of #2170.

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- [x] Add a [CHANGELOG](https://github.com/pyodide/pyodide/blob/main/docs/project/changelog.md) entry
- [x] Add / update tests
- [x] Add new / update outdated documentation

Add `default_converter` argument to `to_js` and `toJs`. This is the mirror image of #2170.

### Checklists

<!-- Note on checklists:
     If you think some of these steps are not necessary for your PR,
     just remove those checkboxes, or mark them as checked. Otherwise,
     if some checkboxes are left unmarked, we might assume that your PR
     is not ready to be merged and we might keep you waiting -->

- [x] Add a [CHANGELOG](https://github.com/pyodide/pyodide/blob/main/docs/project/changelog.md) entry
- [x] Add / update tests
- [x] Add new / update outdated documentation

import pytest


@pytest.mark.driver_timeout(40)
def test_pyb2d(selenium_standalone, request):
    selenium = selenium_standalone
    selenium.load_package("pyb2d")

    selenium.run(
        """
        import numpy as np
        import b2d
        w = b2d.world(gravity=(0,-10))
        """
    )

import pytest


@pytest.mark.driver_timeout(40)
def test_pyb2d(selenium_standalone, request):
    selenium = selenium_standalone
    selenium.load_package("pyb2d")

    selenium.run(
        """
        import numpy as np
        import b2d
        w = b2d.world(gravity=(0,-10))
        """
    )
