Automate integration tests using GitHub Actions

[aneudecker]

Test from tests folder should run automatically with every commit using GitHub actions

Ideas:

• Create cluster in docker container using trivup
• Run tests against cluster using devtools::test()
• Make kafka broker version configurable
• Run on different operating systems

[wahani]

• Action was configured using: https://github.com/r-lib/actions/tree/v2-branch/examples#standard-ci-workflow
• Updates on installation instructions are added to Readme
• Updates on using docker-compose are added to Readme. Setup was created following https://hackernoon.com/setting-up-kafka-on-docker-for-local-development
• docker-compose setup in GitHub action was created following
  • https://stackoverflow.com/questions/65914287/github-action-with-mysql-test-database
  • Add docker and docker-compose to macOS actions/runner-images#17

[wahani]

• Action for ubuntu-latest was added
• Configured portable names in docker-compose.yml to be able to execute docker exec in pipeline step
• Set environment variables to configure topic and brokers to be used in several steps

[wahani]

• On MacOS we have the problem, that environment variables are not picked up in the same way. We have to use .Renviron files to configure BROKERS and TOPIC. This works now.
• We still have an error in the integration tests on MacOS which is reported in Support other operating systems #2

With this we can close this issue.