Add StartOptions and MobileScannerViewAttributes to export to let developers to mock MobileScannerPlatform

Author: a-abramov

lib/mobile_scanner.dart

@@ -25,9 +25,11 @@ export 'src/objects/mobile_scanner_state.dart';
 export 'src/objects/person_name.dart';
 export 'src/objects/phone.dart';
 export 'src/objects/sms.dart';
+export 'src/objects/start_options.dart';
 export 'src/objects/url_bookmark.dart';
 export 'src/objects/wifi.dart';
 export 'src/overlay/barcode_overlay.dart';
 export 'src/overlay/barcode_painter.dart';
 export 'src/overlay/scan_window_overlay.dart';
 export 'src/overlay/scan_window_painter.dart';
+export 'src/mobile_scanner_view_attributes.dart';