[Bugfix] Fix get_quant_config when using modelscope

[Potabk]

Purpose

When one want to use models from modelscope, there appears an issue in the quantization scenario which will only get quant_config from huggingface

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request addresses an issue with loading quantization configurations for models from ModelScope. The fix involves ensuring the model is downloaded before its path is checked, which is a sound approach. However, this introduces a new function, maybe_download_from_modelscope, that is nearly identical to an existing function in another file. I've added a high-severity comment to highlight this code duplication and suggest a refactoring to improve maintainability.

[Isotr0py]

Look reasonable to me!