NeMo - replace named tuples with dataclasses in dataloader returns.
        No action item below, but need to consider long term.

I wonder if we should start moving away from named tuples, switching to data classes instead. NamedTuple somehow interfere with pickling which might become necessary soon with PT 2.0 (maybe)

_Originally posted by @titu1994 in https://github.com/NVIDIA/NeMo/pull/5356#discussion_r1049069660_
      