main library Null safety

1. diginotescreen
2. main library

diginotescreen package

1. Libraries
2. device_info
3. firebase_battery_reporter_provider
4. firebase_battery_reporter_repository
5. firebase_connectivity_provider
6. firebase_connectivity_repository
7. firebase_options
8. firebase_pairing_provider
9. firebase_pairing_repository
10. firebase_preview_provider
11. firebase_preview_repository
12. generated_plugin_registrant
13. header
14. main
15. main_view
16. message_item
17. messages_model
18. pairing_code_text
19. positioned_message_item
20. preview_view
21. qr_code
22. screen_info_model
23. screen_model
24. starter_view
25. timer_provider