feat/auth-export-unmet-password-requirements export

[JoseAlba]

Need to export UnmetPasswordRequirements as developers can not currently override class: InputResolver method: passwordRequires.

Amplify_authenticator is exporting auth_strings_resolver and auth_strings_resolver exports input_resolver. Input resolver has a few methods that are meant to be exposed to the public to be overriden.

file:amplify_authenticator.dart
export 'src/l10n/auth_strings_resolver.dart' hide ButtonResolverKeyType;

file: auth_string_resolver.dart
export 'input_resolver.dart';

In method passwordRequires one of the parameters is of type UnmetPasswordRequirements. Previously the API was called PasswordProtectionSettings which was exported for developer usage.

  String passwordRequires(
    BuildContext context,
    UnmetPasswordRequirements requirements,
  ) 

The solution here is exporting the UnmetPasswordRequirements so that developers can override the InputResolver class. If Amplify doesn't want to continue extending this API, I recommend using the dart keyword sealed so that the class can't be extended.

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[Equartey]

Thanks for the contribution! I left one small request.

[JoseAlba]

Test seems to be failing because of a separate issue. Nothing to be done from this PR likely