[movebase_state_service] Service that returns current costmaps with plans overlaid

This service return the local and global costmaps as image with the global and local plans overlaid. It also returns the last image from the camera. The idea is to use this in `strands_navigation` to get some more info on what happened when the robot failed.

Call the service with `rosservice call /movebase_state_service "save_to_disk: true"` if you want to save the image to `~/.ros/movebase_state_service` or with false if you just want to get the images back as messages.

@bfalacerda Please merge this when you've integrated the service call.