* Use @metamask/eslint-config@1.1.0
* Use eslint-plugin-mocha@6.2.2
* Mark root ESLint config as root
* Update Mocha ESLint rules with shared ESLint config
* eslint: Check for unused function arguments
* eslint: Ignore unused '_' in argument list
Also allow any number of '_' e.g., '__' or '___' which is to be used sparingly
* Remove and rename unused arguments