[SUPPORT REQUEST] Add support for generic Github Actions implementation

[afinetooth]

Via support request, the feature request is to add support for a "Vanilla" implementation of Github Actions, fo users who for one reason or another cannot use the Coveralls Github Action.

The goal would be to add support for Github Actions CI that would not require the Coveralls Github Action, which means populating all JSON params for a user on node-coveralls that is using Github Actions alone. This entails mapping values from the environment like service_job_id.

To distinguish from the Coveralls Github Action, we could also add a usage note to use github for service_name, which would distinguish "vanilla" implementations from Coveralls Github Action ones.

[jtwebman]

Since this library doesn't seem to be supported anymore I fix a bunch of things on a fork if you want to check it out and are still pulling the library into your packages: https://github.com/jtwebman/coveralls-next

I use this version in that library in a very generic way (https://github.com/jtwebman/coveralls-next/blob/master/.github/workflows/test.yml) but I used a different service name to do it as I couldn't figure out their logic for using the tool directly and using the GitHub token instead.