allow loading of sd models from safetensors without online lookups using local config files

[vladmandic]

What does this PR do?

Fixes outstanding critical request that diffusers can use from_single_file method to load safetensors file
without needing to download yaml config file from github

This allows loading of safetensors to be done while offline.

Without this, any attempt to load safetensors model requires connection to github
(e.g. https://raw.githubusercontent.com/CompVis/stable-diffusion/main/configs/stable-diffusion/v1-inference.yaml)

Note that download_from_original_stable_diffusion_ckpt already has defined model_files param and its fully documented,
but it was never actually implemented. this PR completes the implementation in existing code.

Tested in SD.Next:

diffusers_load_config['config_files'] = {
    'v1': 'configs/v1-inference.yaml',
    'v2': 'configs/v2-inference-768-v.yaml',
    'xl': 'configs/sd_xl_base.yaml',
    'xl_refiner': 'configs/sd_xl_refiner.yaml',
}
if hasattr(pipeline, 'from_single_file'):
    diffusers_load_config['use_safetensors'] = True
    sd_model = pipeline.from_single_file(checkpoint_info.path, **diffusers_load_config)

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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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• Did you write any new necessary tests?

Who can review?

@patrickvonplaten and @sayakpaul

[Nuullll]

- Note that download_from_original_stable_diffusion_ckpt already has defined model_files param and its fully documented,
+ Note that download_from_original_stable_diffusion_ckpt already has defined config_files param and its fully documented,

Minor typo :-P

[patrickvonplaten]

That works! Thanks

[Louis24]

still not fixed