Svdquant huggingface checkpoint export support

[sychen52]

What does this PR do?

Type of change: new feature

Overview:

Usage

cd ./examples/llm_ptq/
python hf_ptq.py \
    --pyt_ckpt_path Qwen/Qwen3-4B \
    --export_path /home/scratch.shiychen_coreai/quantized_models/Qwen3-4B-svdq \
    --qformat nvfp4_awq_svdquant --kv_cache_qformat none --sparsity_fmt dense --calib_size 8

Testing

exported checkpoint and loaded.

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• Is this change backward compatible?: Yes/No
• Did you write any new necessary tests?: Yes/No
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Additional Information

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.63%. Comparing base (fe52b2a) to head (2141906).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #754      +/-   ##
==========================================
- Coverage   74.68%   74.63%   -0.06%     
==========================================
  Files         192      192              
  Lines       18950    18995      +45     
==========================================
+ Hits        14153    14177      +24     
- Misses       4797     4818      +21     

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