docs: add Google-style docstrings to auto_round/data_type/ modules
Add or improve module-level, function-level, and inner-function docstrings
across all nine files in auto_round/data_type/:
- __init__.py : module docstring
- register.py : module docstring; expand register_dtype / inner register docs
- utils.py : module docstring; document get_gaudi_fp8_ste_func,
update_fused_layer_global_scales and its inner helpers,
update_block_global_scale_if_needed, pad_sym, pad_bits
- int.py : module docstring; document search_scales
- fp8.py : module docstring
- mxfp.py : module docstring; document quant_element
- nvfp.py : module docstring; document cast_to_fp4, get_reciprocal,
calculate_gparam, ref_nvfp4_quant, nv_fp4,
nv_fp4_with_static_gs, float_to_e5m3_frexp,
e5m3_to_float_tensor, cast_to_ue5m3, cast_to_ue5m3_ste,
ref_fp4_quant, fp4_v2_with_global_scale, fp4_v2
- w4fp8.py : module docstring
- gguf.py : module docstring; document double_quant_tensor,
double_quant_tensor_sym, double_quant_tensor_sym_rtn,
make_qp_quants, _imatrix_handle_zero,
search_gguf_scale_min_asym, iterative_wls_quant_search_chunk,
search_gguf_scale_min_sym
No logic changes; docstrings only.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>