Adds a FlyteCallback
Author: peridotml
Pull request: yes

# What does this PR do?
This PR adds a Flyte callback that integrates with Flyte's [intra-task checkpoints](https://docs.flyte.org/projects/cookbook/en/stable/auto/core/control_flow/checkpoint.html#why-intra-task-checkpoints) and [Flyte Decks](https://docs.flyte.org/projects/cookbook/en/latest/auto/core/flyte_basics/deck.html).

I raised this issue in order to get approval for this PR #23476 

I am using this [example](https://gist.github.com/peridotml/68f376f0f4fd1926fb0746daaeea09f8) to test on a flyte cluster. It uses Flyte's checkpointing system to restart from a hugging face checkpoint (see screenshots).
<img width="400" alt="Screenshot 2023-05-26 at 2 57 59 PM" src="https://github.com/huggingface/transformers/assets/106936600/5cf83157-cce0-4a2e-8a2f-cd1a72c65820">
<img width="400" alt="Screenshot 2023-05-26 at 2 58 14 PM" src="https://github.com/huggingface/transformers/assets/106936600/891d86e7-5885-4851-889f-e912d42f2902">

Once this is merged, I will add this and more to Flyte's documentation.

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Comments:
_The documentation is not available anymore as the PR was closed or merged._

Really thrilled to have this opportunity to contribute! 🎉

Before I transition this PR out of draft mode, I want to ensure everything on the Flyte side is spot on.

- I'm working on linking to a live example on Flyte
- I've also reached out to @cosmicBboy, @kumare3, @zeryx on the Flyte team - who might have some comments. I know they were excited about this integration 😄. 

@sgugger we should be good to go now! I responded to the Flyte team and updated the docs

@sgugger should be good! 🤞