Add AuraFlow GGUF support

[AstraliteHeart]

What does this PR do?

Adds GGUF loading support for AuraFlow via from_single_file, alongside tests, documentation and minor fixes to handle missing bias data in GGUF.

Fixes #10427

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@city96 @hlky @sayakpaul @sayakpaul @DN6 @stevhliu

[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.

[stevhliu]

Thanks!

[AstraliteHeart]

Thank you @hlky and @stevhliu, updated the PR to reflect your feedback.

[DN6]

Thank you 👍🏽