Implement Python code formatting

[sonnyp]

With JavaScript and Rust (and soon Vala) we do 2 things:

1. Workbench auto formats the code when pressing "Run"
2. We have a pre-commit hook that auto formats staged files (see lint-staged in package.json )

We should implement the same thing for Python so that

1. We don't ask contributors to make bothersome code formatting changes
2. Improve the experience of Workbench user