Add proper maneuver icons

[nilsnolde]

For the guidance description we currently show a generic icon, the same for every kind of maneuver. We should add support for arrow-like maneuver icons like all other routing apps. I'm honestly never working with instructions, but I think the osrm format is more suited for guidance instructions, so should probably change to that (if it's not what we're using already, not sure at this point).

[nandalalshukla]

hi @nilsnolde , firstly, thank you for pointing out this issue, it's really interesting to work on!
I have a confusion, what icons should i show, when the maneuver is something like this?
"Enter the roundabout and take the 1st exit onto थापाथली highway"
It contains both enter and exit in the instruction.
I looked the osrm icons, but didn't find such a case.