Introduce pre-commit Python code-formatter

[brodyberg]

Run the Python code-formatter Black via a pre-commit hook. The objective of this is that all code will end up looking the same regardless of author transparently.

[brodyberg]

Please assign to @brodyberg

[brodyberg]

Playing around - I have code-formatting and pytest running prior to a commit:

And pytest integrated into VS Code:

[brodyberg]

Also got code coverage working - will move the test files out to the root-level test folder in order to clear the test files out of the coverage report.