Add basic package structure

[adamltyson]

• Added setup.cfg to define project and requirements
• Added pyproject.toml to define build
• Moved code into cellshape-cloud dir
• Updated .gitignore
• Added versioning tooling using bump2version
• Added structure for tests using pytest
• Added MANIFEST.in
• Added github actions workflow to
  • Run formatting checks (disabled for now)
  • Run tests (only placeholder for now) on macOS, Linux & Windows
  • Package source and wheel distributions
  • Upload to PyPI
• Added .pre-commit-config.yaml to set up automatic running of linting tools (black & flake8). Not run yet.