MLU devices : Checks if mlu is available via an cndev-based check which won't trigger the drivers and leave mlu

[huismiling]

What does this PR do?

MLU devices : Checks if mlu is available via an cndev-based check which won't trigger the drivers and leave mlu

Check devices(cuda and mlu) is available with patch_environment .

Move clear_environment and patch_environment into src/accelerate/utils/environment.py to avoid circular import .

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[huismiling]

@BenjaminBossan @muellerzr
Previous PR #3057 is closed.
Sorry for taking so long time to fix circular import.
clear_environment and patch_environment are moved into src/accelerate/utils/environment.py .