`native_desktop` is not a real target_platform. It is workaround to
specify "build only kiwix-desktop on native_dyn".
It was useful, when we need to build kiwix-desktop on a different build
env than the other project (because of packaging constraints).
Now we can build kiwix-desktop and all other projects on the same build
env, we can remove it and build kiwix-desktop with other `native_dyn`.