Allow for auto-formatting on save when using VSCode

[egibs]

Background

make fmt runs both isort and black on all files in the repository; however, it would also be nice for individual files to be formatted automatically on save. This PR updates the configuration applied by make vscode-config to include settings to run the equivalent of what make fmt runs when saving a file.

This PR also updates the README file with a link to the required VSCode extension and makes a note of the added functionality for the Make target and also adds the black and isort configuration to pyproject.toml.

Changes

• Adds make fmt equivalents to example_settings.json
• Updates README.md
• Adds pyproject.toml

Testing

• The new settings work as expected -- I tested this by running make vscode-config, installing the formatting extension, and saving a modified file with obvious formatting issues which were then resolved on save.