Internal javadoc search doesn't work with JavaFX 22

[petebankhead]

See #1496 and #1358

The workaround in v0.5 was to revert to JavaFX 20, but we don't want to be stuck indefinitely on an out-of-date version. There have been many fixes and improvements, e.g. see

• https://gluonhq.com/products/javafx/openjfx-22-release-notes/
• https://gluonhq.com/products/javafx/openjfx-21-release-notes/

So we need to try to figure out a fix - or document the limitation - for v0.6.