[Train] Add example of pre-training Llama model on Intel Gaudi

[harborn]

Why are these changes needed?

To leverage the potential of Intel Gaudi accelerator, we extend Ray Train's capabilities by adding support for Intel Gaudi (HPU) hardware. This PR include an example for pre-training Llama-7b on multi HPUs.

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Checks

• [ ] I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• [ ] I've run scripts/format.sh to lint the changes in this PR.
• [ ] I've included any doc changes needed for https://docs.ray.io/en/master/.
  • [ ] I've added any new APIs to the API Reference. For example, if I added a method in Tune, I've added it in doc/source/tune/api/ under the corresponding .rst file.
• [ ] I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • [ ] Unit tests
  • [ ] Release tests
  • [ ] This PR is not tested :(