Override the class list via TaxonomyModelTF.from_config()

[IamJeffG]

Context

Sometimes we deal with SavedModels (not built by us) where the class list is not in "labels.csv" but in some other file. In those cases, inference via the SDK's TaxonomyModelTF will fail because the number of shape of output logits does not match the class_list shape.

What I changed

This PR allows downstream users to override the TaxonomyModelTF.class_list when instantiating using the from_config factory method.

My downstream code uses it as follows:

    perch_cfg = ConfigDict()
    perch_cfg.model_path = model_path
    with open(model_path / "reef_label.csv", "r") as f:
        perch_cfg.class_list = namespace.ClassList.from_csv(f)

    model = TaxonomyModelTF.from_config(perch_cfg)

[sdenton4]

Thanks, Jeff!
This should be resolved more generally by #615