Improves lane handling for subsequent going straight, resolves #2625

Before we only worked on subsequent quick turns, as in:
`right, right` keeps the user on the rightmost lanes.

This changeset modifies the logic to work on any subsequent steps
that are "quick" and have lane information we can constrain later.

Because we do not have a from-lane => to-lanes mapping we take the
lanes left and right of the turn lanes into account when heuristically
assigning the leftmost / rightmost lanes.

There are some edge cases where this still does not give us the optimal
solution but it gets close to what is actually possible at the moment
without having a lane mapping in post-processing.

References:
- https://github.com/Project-OSRM/osrm-backend/issues/2625

fix rebase

include/extractor/guidance/toolkit.hpp

@@ -307,8 +307,11 @@ inline bool hasRoundaboutType(const TurnInstruction instruction)
                                                     TurnType::EnterRoundaboutIntersectionAtExit,
                                                     TurnType::ExitRoundaboutIntersection,
                                                     TurnType::StayOnRoundabout};
-    const auto valid_end = valid_types + 13;
-    return std::find(valid_types, valid_end, instruction.type) != valid_end;
+
+    const auto *first = valid_types;
+    const auto *last = first + sizeof(valid_types) / sizeof(valid_types[0]);
+
+    return std::find(first, last, instruction.type) != last;
 }
 
 // Public service vehicle lanes and similar can introduce additional lanes into the lane string that