TF-2667 Use Username replace UserProfile

model/lib/extensions/user_profile_extension.dart

@@ -1,7 +0,0 @@
-import 'package:model/model.dart';
-
-extension UserProfileExtension on UserProfile {
-  UserProfileResponse toUserProfileResponse() {
-    return UserProfileResponse(email);
-  }
-}

model/lib/extensions/username_extension.dart

@@ -0,0 +1,7 @@
+
+import 'package:core/presentation/extensions/string_extension.dart';
+import 'package:jmap_dart_client/jmap/core/user_name.dart';
+
+extension UsernameExtension on UserName {
+  String get firstCharacter => value.firstLetterToUpperCase.toUpperCase();
+}