Gligen training

[Hzzone]

Training GLIGEN Like ControlNet

This PR implements the training code of GLIGEN including making training data, training, and testing. One can use the trained model without any change of diffusers. The original issue has been discussed in issues/7368.

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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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Who can review?

This PR is opened according to the discussion with @sayakpaul.
Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
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[sayakpaul]

Thanks for your awesome contributions! Will merge once the CI is green <3

[sayakpaul]

Hi @Hzzone could you fix the code quality tests?

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.