Prevent assignment to all configs

[danbraunai-apollo]

We want frozen=True on all of our configs. Without this, the user is allowed to assign values to configs. This could cause all kinds of chaos where we store the config at the end in the results file but it doesn't represent what actually happened.

I think we can just add it to the model_config ConfigDict attribute (as in rib.data.DatasetConfig).

[nix-apollo]

Note new_config = config.model_copy(update={"key":new_val}, deep=true) is an option for e.g. tests

[danbraunai-apollo]

Completed in #237