Properly testing the node ordering in `test_featurizer.py`

[DomInvivo]

A new ordered=True option has been introduced to deal with an rdkit issue where the smiles where not re-ordered correctly.

1. Document in Datamol that ordered=True is also useful when dealing with ordered smiles or molecules
2. Properly test the re-ordering in test_featurizer.py

[DomInvivo]

Issue is being fixed in PR #521 , and will be merged on the main with Graphium 3.0 in #519