Country/locale-specific road marking colors

https://github.com/westnordost/StreetComplete/pull/2269 - it is just a PR for now, but by the author and seems to be basically complete, so it should appear soon (posting here early, not after it was released as maybe someone would be interested in reviewing it)

So surveying with StreetComplete will become more useful for people using AB maps of places where they live.