Handle distributed values

[khatchad]

          For [`experimental_distribute_datasets_from_function`](https://www.tensorflow.org/versions/r2.9/api_docs/python/tf/distribute/Strategy#experimental_distribute_values_from_function), that function:

Generates tf.distribute.DistributedValues from value_fn.

Tracking DistributedValues isn't currently supported.

Originally posted by @khatchad in https://github.com/wala/ML/issues/92#issuecomment-1839575322

[khatchad]

DistributedValues seems to be an iterable construct.

[khatchad]

We could treat these as a dataset.