Add regression test for fix of PR #1256

[MichaelBuessemeyer]

Add regression test for fix of PR #1256. This needs to be done in a separate pr as I cannot get the test working and it is important to merge the fix.

Something like this could be used:

# Regression test for: https://github.com/scalableminds/webknossos-libs/pull/1256
@pytest.mark.use_proxay
def test_dataset_access_via_annotation(tmp_path: Path) -> None:
    url = "http://localhost:9000/datasets/Organization_X/l4_sample"
    token = os.getenv("WK_TOKEN")
    with wk.webknossos_context("http://localhost:9000", token):
        dataset_to_reupload = wk.Dataset.download(
            url,
            path=Path(tmp_path) / "sample_ds",
            bbox=wk.BoundingBox((3164, 3212, 1017), (10, 10, 10)),
        )
        renameable_dataset = dataset_to_reupload.upload("name_to_replace")
    path = TESTDATA_DIR / "annotations" / "l4_sample__explorational__suser__94b271.zip"
    annotation_from_file = wk.Annotation.load(path)
    annotation_from_file.organization_id = "Organization_X"
    annotation_from_file.dataset_name = renameable_dataset.name
    annotation_from_file.dataset_id = renameable_dataset._dataset_id
    test_token = os.getenv("WK_TOKEN")
    with wk.webknossos_context("http://localhost:9000", test_token):
        url = annotation_from_file.upload()
        annotation = wk.Annotation.download(url)
    assert annotation.dataset_name == "name_to_replace"
    assert len(list(annotation.skeleton.flattened_trees())) == 1

    renameable_dataset.name = "replaced_name"
    # Test whether the DS can still be accessed via the annotation after the renaming.
    dataset_from_annotation = annotation.get_remote_annotation_dataset()
    assert dataset_from_annotation._dataset_id == renameable_dataset._dataset_id