Add Java 17 and remove Java 8

[scholzj]

It is time to move on -> this PR drops the Java 8 support for this plugin and moves it to Java 11+ only. As a part of that, it:

• Removes the Java 8 pipeline form the CI
• Add a new Java 17 pipeline to the CI
• Updates the dependencies and various Maven plugins to make it compatible with Java 17
• Fixes some Javadoc issues to make it compatible with Java 17
• Removes some use of deprecated methods in tests