Add python package convert_meshes for mesh conversion

python/convert_meshes/README.rst

python/convert_meshes/bin/convert_meshes

python/convert_meshes/convert_meshes/__init__.py

python/convert_meshes/convert_meshes/convert_meshes.py

python/convert_meshes/pyproject.toml

python/convert_meshes/setup.py

python/convert_meshes/tests/__init__.py