Prettier had some missing extensions in the config, this commit
added them, we then prettified the whole project. We
ignore the `cunningham-tokens` files.
Eslint extension highlighted some issues with the way we were
importing the tsconfig.json file in the .eslintrc.json file.
By changing the extension to .cjs, we are now able to set
tsconfigRootDir to the root of the package thanks to `dirname`.
It helps eslint to find the correct tsconfig.json file.
