Enhance `_download_from_ngc` to support no-prefix or different prefix data

[yiheng-wang-nv]

So far, it's alway use the default prefix:

def _download_from_ngc(
    download_path: Path, filename: str, version: str, remove_prefix: str | None, progress: bool
) -> None:
    # ensure prefix is contained
    filename = _add_ngc_prefix(filename)
...

We can make use of _add_ngc_prefix's prefix arg