Mirror HF summarization example with PiPPy

[pbelevich]

1. Create a branch hf_example_summarization
2. Copy summarization dir to hf
3. Add files, commit, create a PR(hf_example_summarization->main)
4. Create another branch hf_example_summarization_pippy on top of hf_example_summarization and all PiPPy changes there
5. Look at https://github.com/pytorch/PiPPy/pull/359 especially examples/hf/translation/run_translation.py and do the changes in run_summarization.py accordingly
6. Add run_summarization.py test to .github/workflows/ci_tests.yaml (see https://github.com/pytorch/PiPPy/pull/359)
7. Add files, commit, create another PR(hf_example_summarization_pippy->hf_example_summarization)

This is a subtask of https://github.com/pytorch/PiPPy/issues/301

[pbelevich]

please use T5 and BART for summarization