Platform preferences theme detection

[Christopher Schnick]

Hello,

I just tried out the new 22-ea+27 build to see whether we can utilize 
some of the new features, particularly the platform preferences API, to 
replace the library https://github.com/Dansoftowner/jSystemThemeDetector 
that we are currently using for theme detection.

I'm running this on Windows 10 with the latest updates and the color 
scheme always reports LIGHT, even when dark mode is enabled in the 
settings. The observable value also does not update when the value 
changes in the settings. Obviously I have a few questions here:
- Should this feature work in that ea version?
- Is Windows 10 supported by the color scheme detection?
- The documentation says that LIGHT is returned in case theme the 
detection is not supported. But I guess there is no way to find out 
whether querying that property is supported on the current system? It 
might be useful in some circumstances to adapt the behavior when we know 
that this is not supported.
- The documentation mentions that some preferences might not be 
available on the current system. Does that mean that if they are 
available, they are also observable? Or might it be possible that a 
certain setting is available but does not support dynamically updating 
at runtime and cannot be observed?

Best regards
Christopher