Add example, that uses only `MapboxCoreNavigation` framework.

[MaximAlien]

Such example can be used to showcase how fully custom UI functionality can be implemented that is based on MapboxCoreNavigation only. UI part can be implemented using MapboxMaps.

[1ec5]

Even better, how about an example that literally only uses MapboxCoreNavigation for a headless navigation experience? Sometimes a developer comes along wanting to build something like that but gets intimidated by needing to strip down our UI-heavy examples.