chore(types): fill out remaining partial types. <!-- Thank you for contributing to Pyodide! All improvements are welcome,
     so don't be afraid to make a PR. -->

### Description

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     - reasoning for the change
     - some details of updated code
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	Please refer to any related issues by #<issue_id> -->

Filling out remaining partially typed functions. Had to guess on a few, maybe some Any's could be avoided.

from pyodide_test_runner import run_in_pyodide


@run_in_pyodide(packages=["xarray"])
def test_xarray(selenium):
    import xarray as xr

    da = xr.DataArray(data=[[0, 1, 2], [3, 4, 5]], dims=("x", "y"))
    xr.testing.assert_equal(a=da.mean(), b=xr.DataArray(data=2.5))

from pyodide_test_runner import run_in_pyodide


@run_in_pyodide(packages=["xarray"])
def test_xarray(selenium):
    import xarray as xr

    da = xr.DataArray(data=[[0, 1, 2], [3, 4, 5]], dims=("x", "y"))
    xr.testing.assert_equal(a=da.mean(), b=xr.DataArray(data=2.5))
