support quant

[liusy58]

Motivation

Modifications

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Accuracy Test

Benchmark & Profiling

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[gemini-code-assist]

Code Review

This pull request introduces support for quantization in the SGLang backend by adding a new sglang_quantization argument to the SGLangBackendArgs class. The changes include updating the argument parser, the factory method, and the keyword argument conversion. A review comment suggests accessing the new attribute directly in the from_args method to maintain consistency with existing fields, as the attribute is guaranteed to be present.

[gemini-code-assist]

For consistency with the other sglang_* fields in this method (lines 189-200), you should access args.sglang_quantization directly. Since this argument is explicitly added to the parser in the add_args method of this class, it is guaranteed to be present in the args namespace when from_args is called.

Suggested change

	sglang_quantization=getattr(args, "sglang_quantization", None),
	sglang_quantization=args.sglang_quantization,