Include full Dockerfile for FSDP example

[sean-smith]

This fixes #491

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[mnuyens]

@sean-smith This change will make it so that the example can only be executed on hosts with cuda installed because GDRCopy fails if you don't. This will render it unuseable on many hosts that currently run the example.

[mnuyens]

@sean-smith if you update the Dockerfile to pin a few version the example works again

RUN pip install torchvision torchaudio transformers==4.46.1 datasets fsspec==2023.9.2 python-etcd numpy==1.*
RUN pip install torch==2.5.1+cu121 --index-url https://download.pytorch.org/whl/cu121