Add some info about the last state on route completion

[ianthetechie]

Currently the complete variant of TripState doesn't have any associated data. We should probably hoist at least the last visual instruction so it remains on screen.

Anything else to add on this @Archdoog?

[Archdoog]

It should already have some associated data:

    /// The navigation controller has reached the end of the trip.
    Complete {
        user_location: UserLocation,
        /// Information pertaining to the user's full navigation trip. This includes
        /// simple stats like total duration, and distance.
        summary: TripSummary,
    },

I'd propose we add:

1. The last visual instruction as you mentioned.
2. The destination/last waypoint. This would allow a developer (or future ferrostar behavior) to retry getting to the destination if someone remains on navigating after arrival.