Update FlatLaf from 2.5 to 2.6

[DevCharly]

Update FlatLaf to v2.6.

This version now uses System.loadLibrary() to load native libs (as suggested here),
always loads libjawt (as suggested here)
and fixes some minor issues.

Changes: https://github.com/JFormDesigner/FlatLaf/releases/tag/2.6

[neilcsmith-net]

Thanks @DevCharly Only minor niggle would be that this now should allow the native libraries to go in arch/OS specific paths like the others. @matthiasblaesing ??

[mbien]

restarted CI with all tests active

[mbien]

#4803 broke platform/core.startup tests (restarted twice):
https://github.com/apache/netbeans/actions/runs/3272323634
exit code 1. So probably JVM crash - haven't investigated further.

This is fixing it. We should get this in ;)

[matthiasblaesing]

Looks sane to me. Verified on OpenJDK 17 on amd64 that the native library is loaded via the NetBeans mechanism (single stepped through org.netbeans.StandardModule.OneModuleClassLoader.findLibrary(String))

[neilcsmith-net]

@mbien wasn't a JVM crash. The CachingPreventsFileTouchesTest was failing, either due to use of InstalledFileLocator in validate() or my suggestion to use the parent directory directly as the argument.

Possibly a sign we should be running platform tests more often?

[mbien]

@neilcsmith-net agreed, I had the same thought. I could make UI trigger platform tests since it doesn't do anything right now. Or we should just use Platform more often?

but in general: if we upgrade a library which is used everywhere, we should add ci:all-tests. I missed that one too, I thought commit validation would catch a problem like this one.