feature: support passing in `.nycrc-path` to `nyc`

https://github.com/cypress-io/code-coverage/blob/8f6154a48ef9256e4d3b57a2387d59c046aba12e/task.js#L103-L108

Currently, this will only allow us to lookup the `.nycrc` from the working directory. However, in the event you are using this from something that is not in the current working directory (like a CLI with predefined configs), we can't point the nyc runner to a different file location on disk to look for the rc file. My request is that an option be added that would allow me to pass in an `nycrc` path to get the rc file, and if none is passed use the default