feat(examples): add zones geojson example

[cpcloud]

Adds a zones geospatial data example

Closes #7958.

[ncclementi]

We should add a test that looks something like this:

def test_load_geo_example():
    pytest.importorskip("duckdb")
    
    con = ibis.duckdb.connect()
    
    t = getattr(ibis.examples, "zones").fetch(backend=con)
    assert t.columns == ['zone', 'LocationID', 'borough', 'x_cent', 'y_cent', 'geometry']

[ncclementi]

xref, closes: #7958

[ncclementi]

Thanks @cpcloud this LGTM!