Missing script to train the entropy model

Hello!
It seems `entropy_model.py` only has scripts to load the entropy model checkpoint.
I was wondering if you could share the scripts used to train the entropy model?

It would tremendously help with training BLT in different domains!

Start by reading entropy_model.py and identify how it currently loads the entropy model checkpoint. Determine whether the training scripts exist elsewhere in the repository; done means providing the scripts needed to train the entropy model for different domains, with enough context to run them.

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