Update Java to 25

[tonihele]

Update Java to 25. Let's do this once we are preparing for 3.9.0 release. One thing though, those SDK example games... They should be updated as well, otherwise they might not run. SDK then would ship with Java 25 and the example games should use that, also perhaps use updated jME version as well. Of course someone downloading those from older SDK might not get them to work without fiddling with Java versions.