RoutesPreview 
    Parameters
- previewed routes ordered in way specific for mapbox navigation: primary, alternative1, alternative2. 
- alternative metadata for valid alternatives from routesList. AlternativeRouteMetadata.alternativeId is always 0 in preview. 
- original routes list which doesn't change order no matter which primary route is selected. 
- index of primary route from the originalRoutesList. 
Use routesList when you want to pass routes to other Navigation SDK components, for example start active guidance calling MapboxNavigation.setNavigationRoutes or display a route using route line API. The majority of the Navigation SDK's API accepts routes in this format.
Use originalRoutesList and primaryRouteIndex if you want to display routes as a list on UI. In this case routes' order shouldn't change on UI when users pick different routes as primary. MapboxNavigation.changeRoutesPreviewPrimaryRoute is designed to select a new primary route without changing the order of the originalRoutesList.