fix: update l10n configuration to use new format

Author: Anton-Dodonov

pubspec.yaml

@@ -107,12 +107,16 @@ flutter:
   # For details regarding fonts from package dependencies,
   # see https://flutter.dev/to/font-from-package
 
-  generate: true
-  
-  
+  # generate: true
 
+flutter_gen:
+  output: lib/gen/
+  line_length: 80
+
 l10n:
   arb-dir: l10n
   template-arb-file: app_en.arb
   output-localization-file: app_localizations.dart
+  output-class: AppLocalizations
+  output-dir: lib/l10n
   untranslated-messages-file: lib/l10n/untranslated_messages.txt