Preferred lane direction should be a ManeuverDirection, not a LaneIndication

[1ec5]

Intersection.validIndication and the preferredDirection associated value of VisualInstruction.Component.lane(indications:isUsable:preferredDirection:) are of type LaneIndication as of #529. But LaneIndication is an option set containing zero or more indications, whereas this property and associated value need to represent one and only one indication. ManeuverDirection has the same cases as LaneIndication but is always a single value. That would allow us to avoid the hack in #529 (comment) #532 (comment) and also allow the navigation SDK to avoid having to convert from LaneIndication to ManeuverDirection in places where it’s already using the primary maneuver direction to influence lane arrow highlighting.

mapbox-directions-swift/Sources/MapboxDirections/VisualInstructionComponent.swift

Line 77 in 399d28c

case lane(indications: LaneIndication, isUsable: Bool, preferredDirection: LaneIndication?)

This change would need to take place in v2.0.0 to avoid breaking backwards compatibility.

/cc @mapbox/navigation-ios

[zugaldia]

This change would need to take place in v2.0.0 to avoid breaking backwards compatibility.

Let's prioritize this work to make sure we don't miss the window.

/cc: @truburt

[jill-cardamon]

PR for this ticket: #535
Double checking tests with Directions API response now.