Added Last Name display and made it editable

frontend/pshared/lib/provider/account.dart

@@ -203,6 +203,7 @@ class AccountProvider extends ChangeNotifier {
 
   Future<Account?> update({
     Describable? describable,
+    String? lastName,
     String? locale,
     String? avatarUrl,
     String? notificationFrequency,
@@ -213,6 +214,7 @@ class AccountProvider extends ChangeNotifier {
       final updated = await AccountService.update(
         account!.copyWith(
           describable: describable,
+          lastName: lastName,
           avatarUrl: () => avatarUrl ?? account!.avatarUrl,
           locale: locale ?? account!.locale,
         ),
@@ -250,10 +252,11 @@ class AccountProvider extends ChangeNotifier {
     }
   }
 
-  Future<Account?> resetUsername(String userName) async {
+  Future<Account?> resetUsername(String userName, {String? lastName}) async {
     if (account == null) throw ErrorUnauthorized();
     return update(
       describable: account!.describable.copyWith(name: userName),
+      lastName: lastName ?? account!.lastName,
     );
   }