Move the build from Travis to GitHub Actions

[cxbrooks]

I got a start on setting up GitHub actions and have something that configures and runs ant, see https://github.com/icyphy/ptII/blob/cxbrooks-github-actions-1/.github/workflows/github-actions-ptII.yml

The devil is in the details. To run all the tests, there is quite a bit of configuration of optional packages that needs to be done. The Travis build is split up in to a bunch of different subsets of the tests that generate xml and then a final step collates all the xml and generates https://www.icyphy.org/ptII-test/reports/junit/html/index.html

As far as moving to GitHub actions, there are these components:

• Run the tests and update the gh-pages branch with the results
• Install the optional components, which are currently done in ptII/.travis.yml. We could create a separate script
• Figure out how to cache and use files generated by GitHub actions. For example, the javadoc output and OpenCV.
• If necessary, figure out how to run GitHub actions jobs longer than 6 hours.