Auto detect interface theme

[rollingmoai]

Is your feature request related to a problem? Please describe. Automatically set interface theme based on system preference.

Describe the solution you'd like If system theme is dark, then interface theme should be dark and vice versa.

Describe alternatives you've considered None.

Additional context None.

[tsl0922]

I don't have a portable way to detect it, so It's not supported yet.

[tsl0922]

https://github.com/glfw/glfw/pull/2260