Check for invalid keys

[muellerzr]

What does this PR do?

This PR introduces a better error when loading the YAML file in by letting the user know what errors were actually present.

Fixes # (issue)

Helps relieve the confusion when getting errors such as:

ClusterConfig.__init__() got an unexpected keyword argument 'myargument'

And instead results with:

Unknown keys in the config file: ['myargument'], please try upgrading your `accelerate` version or remove them.

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• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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@BenjaminBossan

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[BenjaminBossan]

Big 👍 for improving error messages, thanks for that. I have some comments, please take a look.

[SunMarc]

LGTM with @BenjaminBossan comments !

[BenjaminBossan]

Thanks, looks good to me.

Nano-nit, if len(extra_keys) > 0 could be if extra_keys, but I'm totally fine as is.