Visualize lane closures

[Yadunund]

Feature request

Description

With the support for lane closures [https://github.com/open-rmf/rmf_traffic/pull/11], it will be useful if the nav graph visualization takes into account which lanes are closed and render without them or with reduce opacity.

Implementation considerations

The rmf_schedule_visaulizer which publishes markers for rendering the navigation graphs can subscribe to /closed_lanes. However, there is no source of mapping between fleet_name and nav_graph index which makes things tricky.