Staircase/steps scribble type

[Colbertson]

Add a step scribble type, footway/path is usually easy enough to see from aerial but steps are more specific
Maybe style it with arrows to indicate which way leads up
(Not sure if I should have posted this as an everydoor issue)

[Zverik]

Yeah this should go to Every Door — this backend doesn't know anything about specific categories.

But then, steps don't occur very often so idk. Would be possible with Zverik/every_door#119 if/when I get a grant for that :)