modify save model in lite module

[43758726]

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[lvhan028]

copy_others is unclear. It copies everything except weight files. Prefer copy_non_weight_files with src_dir / dst_dir.
It is shared by multiple APIs, so don’t keep it in auto_awq.py. Rename load.py → io.py and put this helper there, then import from lmdeploy.lite.utils.io.