Update to javafx 16

[Siedlerchr]

https://github.com/openjdk/jfx/blob/master/doc-files/release-notes-16.md

• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked documentation: Is the information available and up to date? If not created an issue at https://github.com/JabRef/user-documentation/issues or, even better, submitted a pull request to the documentation repository.

[tobiasdiez]

Cool! It is working without a problem locally?

Could you please also revert #5497 since the javafx bug is now fixed. According to #5226 that's the only issue that was waiting on a javafx update.

[Siedlerchr]

Reverting #5497 would create a merge conflict with #7336
Worked fine locally