fixed an issue where remaining waypoints would always return 0 and break reroute handling

[LukasPaczos]

Description

Fixes a regression from 769430a which caused a crash when a reroute event happens due to a misreported remaining waypoints count, example stacktrace:

Process: com.mapbox.navigation.instrumentation_tests, PID: 15480
    java.lang.IllegalStateException: At least 2 coordinates should be provided.
        at com.mapbox.navigation.route.offboard.router.MapboxDirectionsUtilsKt.routeOptions(MapboxDirectionsUtils.kt:20)
        at com.mapbox.navigation.route.internal.offboard.MapboxOffboardRouter.getRoute(MapboxOffboardRouter.kt:53)
        at com.mapbox.navigation.route.internal.hybrid.MapboxHybridRouter$RouterHandler.handleRouteRequest(MapboxHybridRouter.kt:182)
        at com.mapbox.navigation.route.internal.hybrid.MapboxHybridRouter$RouterHandler.getRoute(MapboxHybridRouter.kt:160)
        at com.mapbox.navigation.route.internal.hybrid.MapboxHybridRouter.getRoute(MapboxHybridRouter.kt:205)
        at com.mapbox.navigation.core.directions.session.MapboxDirectionsSession.requestRoutes(MapboxDirectionsSession.kt:81)
        at com.mapbox.navigation.core.reroute.MapboxRerouteController.request(MapboxRerouteController.kt:101)
        at com.mapbox.navigation.core.reroute.MapboxRerouteController.reroute(MapboxRerouteController.kt:58)
        at com.mapbox.navigation.core.MapboxNavigation.reroute(MapboxNavigation.kt:738)
        at com.mapbox.navigation.core.MapboxNavigation.access$reroute(MapboxNavigation.kt:129)
        at com.mapbox.navigation.core.MapboxNavigation$createInternalOffRouteObserver$1.onOffRouteStateChanged(MapboxNavigation.kt:732)
        at com.mapbox.navigation.core.trip.session.MapboxTripSession.setOffRoute(MapboxTripSession.kt:123)
        at com.mapbox.navigation.core.trip.session.MapboxTripSession.access$setOffRoute$p(MapboxTripSession.kt:48)
        at com.mapbox.navigation.core.trip.session.MapboxTripSession$updateDataFromNavigatorStatus$updateNavigatorStatusDataJob$1.invokeSuspend(MapboxTripSession.kt:487)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at androidx.test.espresso.base.Interrogator.loopAndInterrogate(Interrogator.java:148)
        at androidx.test.espresso.base.UiControllerImpl.loopUntil(UiControllerImpl.java:519)
        at androidx.test.espresso.base.UiControllerImpl.loopMainThreadUntilIdle(UiControllerImpl.java:441)

This PR resolves the issue by checking the coordinates count instead of waypoints indices count which reports a different value and adds an instrumentation regression test.

Changelog

<changelog>Fixed a crash when rerouting and fixed a misreported remaining waypoints count that was the root cause.</changelog>

[korshaknn]

just some nits