Add Hex Coordinates

[timskap]

Example:

struct HashableCLLocationCoordinate2D: Hashable {
    let latitude: Double
    let longitude: Double
    
    init(_ coordinate: CLLocationCoordinate2D) {
        self.latitude = coordinate.latitude
        self.longitude = coordinate.longitude
    }
}

let resolution = 5
            let ringSize = 30
            let h3Index = H3Index(coordinate: H3Coordinate(lat: locationCoordinate.latitude, lon: locationCoordinate.longitude), resolution: Int32(resolution))
            let ringIndexes = h3Index.kRingIndices(ringK: Int32(ringSize))
            
            hexCoordinates = ringIndexes.map { index in
                let coordinates = index.boundary()
                return coordinates.map { coordinate in
                    HashableCLLocationCoordinate2D(CLLocationCoordinate2D(latitude: coordinate.lat, longitude: coordinate.lon))
                }
            }

[plz-review]

Review this PR using plz

[timskap]

I fix an issue with stdrup in file. Should work now.