Add pre-commit hooks to automate code formatting

[AlexIoannides]

"As a Bodywork Developer, I would like code formatting to be executed automatically prior to making a commit, so that I don't have to remember to run all the formatting tools and each commit is consistently formatted."

Tasks

• Read about the pre-commit package.
• Setup the pre-commit package.
• Add Black, isort and pydocstyle as pre-commit hooks.
• Document the installation steps required by new developers.

Requires #197, #196 to be completed first.