Add identifier to MapMatchingResponse

[1ec5]

Per mapbox/mapbox-java#1174, the Mapbox Map Matching API will start returning a uuid field for all successful map matching requests. MapMatchingResponse should have an identifier property similar to the existing RouteResponse.identifier property, decoding it when uuid is present in the response.

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

Line 11 in b7c26f5

public let identifier: String?

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

Line 33 in b7c26f5

case identifier = "uuid"

RouteResponse(matching:options:credentials:) should pass in the value of this new property instead of nil:

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

Line 71 in b7c26f5

self.init(httpResponse: response.httpResponse, identifier: nil, routes: routes, waypoints: waypoints, options: .match(options), credentials: credentials)

Unlike mapbox/mapbox-java#1174, this work is not blocked by deploying the change to all profiles, because the identifier property would be optional.

/cc @mapbox/navigation-ios @danpaz