Bus lanes with a center turn lane break

[dabreegster]

lanes:both_ways=1 and something like bus:lanes:backward=||designated don't work together, due to https://github.com/a-b-street/osm2lanes/blob/7f64330d31eb7b263e7bc65f8302a79c8d7f46d8/osm2lanes/src/transform/tags_to_lanes/modes/bus/mod.rs#L153 counting the both-ways lane in road.len().

Example is https://www.openstreetmap.org/way/753045259