Minimize depdencies fetched by using net.corda:jfx

[koppor]

This is to reduce the mass of transitive dependencies fetched by using corda.net. See #3014.

• Change in CHANGELOG.md described
• Tests created for changes
• Screenshots added (for bigger UI changes)
• Manually tested changed features in running JabRef
• Check documentation status (Issue created for outdated help page at help.jabref.org?)
• If you changed the localization: Did you run gradle localizationUpdate?

[Siedlerchr]

Looks like a workaround, I think we just should convert the list class

[lenhard]

The conversion would be the more desirable solution.

But if we don't get the conversion done before the release of 4.0, we might consider to merge it anyway. I'd say: Let's keep this PR open until either someone does the conversion or we want to release 4.0.

[koppor]

I assigned #3014 to a milestone, so we are reminded that there is some work left.

I will merge this in as it will surely reduce the size of our JAR.