Switch CI to GitHub actions

[codefromthecrypt]

travis-ci.org is being shut down the end of the year. We tried switching to travis-ci.com, but shortly ran out of quota. For the last two weeks we have not succeeded in getting classified as OSS or even a temporary quota increase. In response to this, all the other projects have moved, or are in the process of moving to GitHub Actions.

While at it, we are standardizing build script and job names for easy reference when people switch from one project to another. It is important that the tasks done in CI do not heavily rely on CI specific tools as in the future we may get into trouble like this again. For example, in the past we had to switch from travis to circle back to travis. Using scripts we control as entrypoints gives us flexibility as CI providers change their policies around open source communities.

Here is an example that follows conventions and might be helpful here: openzipkin/zipkin-ruby#180

[jcchavezs]

Pinging @peter279k as he helped a lot with other migrations around zipkin <3

[jcchavezs]

@peter279k did you have time to jump into this?

[peter279k]

Sorry. I have no available time to work on that.