ShippingAddress.fromJson constructor
Creates a ShippingAddress object from JSON object
Implementation
factory ShippingAddress.fromJson(Map<String, dynamic> json) {
  return ShippingAddress(
    countryCode: json['country_code']!,
    state: json['state']!,
    city: json['city']!,
    streetLine1: json['street_line1']!,
    streetLine2: json['street_line2']!,
    postCode: json['post_code']!,
  );
}