Add CI pipeline for testing (GitHub Actions)

[Cherry]

This includes linting, and then testing on supported Node versions. https://travis-ci.org/ is probably the best idea.

For running the test.js, we need to think about how to do that in a way that won't expose any credentials. Perhaps we need to stub Cloudflare's API as well as http/dns to faux-verify? I'm not sure about the best way to implement this yet.

[Cherry]

Marking this for hacktoberfest.

We should use GitHub Actions. Please see nodecraft/b2-cloud-storage#14 for an example on what needs to be included (code coverage can be ignored for now).

This could be two PRs - one for adding GitHub actions that simply runs npm test for now, and another one for a testing strategy for test.js

[abskmj]

I can pick this up. I can work on the first PR for adding the Github Action.

[Cherry]

Thanks @abskmj! Let be know if you have any questions.

[abskmj]

Hello @Cherry, I have opened a new PR #19 with assumptions. Can you take a look?

[Cherry]

Looks great, thanks @abskmj!