Support `--path` option

In multi-package repo, I'd like to be able to use different commitlint configurations per package. Therefore with commitlint CLI I'd like to be able to validate commits that affect a given path only.

It'll be great if `--path` option is supported so we can narrow the list of validated commits to one affecting a specific directory (e.g. `standard-version` which generates changelog by retrieving commits supports `path` option, with commitlint it's not possible)