Make GH Action work with PRs from forked repos

They currently fail because they cannot access the GITHUB_TOKEN nor SONAR_TOKEN (as both are secrets). Probably switching to https://docs.github.com/en/actions/learn-github-actions/events-that-trigger-workflows#pull_request_target is required.

In addition GH actions should build with Java 8, 11, 17 on Linux, Windows and Mac.