add messages about offline status in onboarding screens

assets/translations/en.json

assets/translations/es.json

assets/translations/fr.json

lib/providers/substrate_sdk.dart

lib/screens/common_elements.dart

lib/screens/home.dart

lib/screens/myWallets/restore_chest.dart

lib/screens/onBoarding/1.dart

lib/screens/onBoarding/10.dart

lib/screens/onBoarding/2.dart

lib/screens/onBoarding/3.dart

lib/screens/onBoarding/4.dart

lib/screens/onBoarding/5.dart

lib/screens/onBoarding/6.dart

lib/screens/onBoarding/7.dart

lib/screens/onBoarding/8.dart

lib/screens/onBoarding/9.dart

pubspec.yaml