Upgrading Python packaging mechanism

[qiyunzhu]

The followin changes were made:

1. Let Click CLI import workflows in a lazy manner, which significantly accelerated loading.
2. Used pyproject.toml instead of setup.py for build configuration.
3. Used hatch instead of setuptools as the build backend.
4. Used environment.yml instead of conda_requirements.txt for conda configuration.
5. Added MacOS and Windows to the CI OS matrix.
6. Added 3.10 to the CI Python version matrix.
7. Removed the "tools" submenu.