[Feature request] Add Fairscale support

[jordiae]

Adding support for Fairscale would be a great addition.

[OhadRubin]

@sgugger Can you address this?

[sgugger]

It is on the roadmap :-)

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

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[muellerzr]

As the Trainer dropped fairscale support, we will not be doing so in Accelerate :)