Automated tests to assure compatibility with java 8, 9, 10, 11, 12

While we still want to compile cli with JDK 8, we want to assure its compatibility with java 8, 9, 10, 11, 12.

All Oracle versions supported by utPLSQL are also supported by a corresponding ojdbc8-driver.

We might need to introduce some kind of cli-testing software and have system tests against the compiled/assembled jars.