Add Google-style docstrings to auto_round/utils/ modules
Added/improved module-level, class, and function docstrings following
Google-style format for:
- auto_round/utils/__init__.py
- auto_round/utils/common.py
- auto_round/utils/distributed.py
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
