Bump minimum JDK version for JavaFX to JDK 22

Even though we build JavaFX binaries with JDK 22 as the boot JDK (see JDK-8336633), the latest version of JavaFX still builds and runs with JDK 21, although it isn't tested with older JDK versions.

In order for JavaFX to be able to use newer JDK features, such FFM (Panama), we need to increase the minimum version of the JDK that can run the latest JavaFX. Additionally, there is an ongoing cost to keeping JavaFX buildable and runnable on older versions of Java, and little reason to continue to do so.

This JBS issue proposes to bump the minimum version of the JDK needed to run JavaFX to JDK 22. This enhancement must not be backported to any earlier version.