Last minute changes

[nohe427]

Some last minute changes that are ready for Firebase Summit 2022

Pre-launch Checklist

• [x] I read the Effective Dart: Style recently, and have followed its advice.
• [x] I signed the CLA.
• [x] I updated/added relevant documentation (doc comments with ///).
• [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-devrel channel on Discord.

[domesticmouse]

Please fix:

Analyzing step_09...

   info - lib/main.dart:216:8 - Name non-constant identifiers using lowerCamelCase. - non_constant_identifier_names
   info - lib/main.dart:216:8 - Private field could be final. - prefer_final_fields
   info - lib/main.dart:217:12 - Name non-constant identifiers using lowerCamelCase. - non_constant_identifier_names
   info - lib/main.dart:219:10 - Name non-constant identifiers using lowerCamelCase. - non_constant_identifier_names
   info - lib/main.dart:219:10 - Private field could be final. - prefer_final_fields
   info - lib/main.dart:220:14 - Name non-constant identifiers using lowerCamelCase. - non_constant_identifier_names
   info - lib/main.dart:222:10 - Name non-constant identifiers using lowerCamelCase. - non_constant_identifier_names
   info - lib/main.dart:222:10 - Private field could be final. - prefer_final_fields
   info - lib/main.dart:223:14 - Name non-constant identifiers using lowerCamelCase. - non_constant_identifier_names
   info - lib/src/authentication.dart:10:10 - Name non-constant identifiers using lowerCamelCase. - non_constant_identifier_names
   info - lib/src/authentication.dart:15:14 - Name non-constant identifiers using lowerCamelCase. - non_constant_identifier_names