* Fix require-unicode-regexp issues
See [`require-unicode-regexp`](https://eslint.org/docs/rules/require-unicode-regexp) for more information.
This change enables `require-unicode-regexp` and fixes the issues raised by the rule.
* Remove case-insensitive flag from regexps
* 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
This was done to reduce the number of direct dependencies we have. It
should be functionally equivalent. The bundle size should not change,
as we use `clone` as a transitive dependency in a number of places.
* 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
