[Experiment] New NavigationView with route-based navigation about fabulous.xamarinforms HOT 4 OPEN

NavigationView(stack: NavigationStack, onPush: NavigationStack -> 'msg, onPop:  NavigationStack -> 'msg) {
        Route(key: string, viewFn: obj -> WidgetBuilder<'pageMsg, #IView>, mapMsgFn: int * 'pageMsg -> 'rootMsg)
        Route(...)
        Route(...)
    }

// We can add some extension methods on Route i.e
Route(...)
    .isRoot(true)
   ....

let update navStack msg model =
        match msg with
        | GoBack ->
            navStack.pop(fun model -> if model.myProperty then `pop the stack` else ` no `)
            model
        | GoToDetail id ->
            navStack.push(
               fun model -> if model.myProperty then  Pages.list, DetailPage.init id else ...)
            model