Add time zone validation to PreferencesViewModel

This prevents users from being setting an invalid time zone through the
account preferences page. In practice this is only likely to occur if
the user has deliberately tampered with the select options, but is still
worth checking to prevent invalid data being stored in the database.

Author: smfeest

src/Buttercup.Web/Models/Account/PreferencesViewModel.cs

@@ -1,4 +1,5 @@
 using System.ComponentModel.DataAnnotations;
+using Buttercup.Application.Validation;
 using Buttercup.EntityModel;
 
 namespace Buttercup.Web.Models.Account;
@@ -12,5 +13,6 @@ public PreferencesViewModel()
     public PreferencesViewModel(User user) => this.TimeZone = user.TimeZone;
 
     [Required(ErrorMessage = "Error_RequiredField")]
+    [TimeZone]
     public string TimeZone { get; init; } = string.Empty;
 }

src/Buttercup.Web/Models/Account/PreferencesViewModel.fr.resx

@@ -3,4 +3,7 @@
   <data name="Error_RequiredField">
     <value>Ce champ est requis</value>
   </data>
+  <data name="Error_InvalidTimeZone">
+    <value>Le fuseau horaire sélectionné n’est pas pris en charge</value>
+  </data>
 </root>

src/Buttercup.Web/Models/Account/PreferencesViewModel.resx

@@ -3,4 +3,7 @@
   <data name="Error_RequiredField">
     <value>This field is required</value>
   </data>
+  <data name="Error_InvalidTimeZone">
+    <value>Selected time zone is not supported</value>
+  </data>
 </root>