Provide GResources example

[gavr123456789]

Generally it is possible to use resource files merged with the executable program instead of an external XML files, we have to investigate how we can do that in Nim. And it may be possible to connect the signal handlers to handler procs from within the XML file — this is also work in progress…

Minimal app example:
https://github.com/nahuelwexd/gtk-vala-template/blob/main/src/ui-resources.xml

[StefanSalewski]

Please provide detailed instructions how to build the final executable with external resources for various compilers and various OS. I somehow managed it for NEd five years ago, but I never understand it, I think I asked in Nim forum or in GTK forum, but as generally no helpful reply, so I collected various google hints until I got a working executable. But I did not understood the details.

[gavr123456789]

I wrote a GSettings guide 1 year ago for vala meson, I think it can be usefull.
https://www.reddit.com/r/vala/comments/g87x6u/how_to_add_gsettings_support_to_meson_project/
I will look into this later.