V15: User password resetting notification (#18679)

* Introduce UserPasswordResettingNotification

* Removed changes to IUserService interface.

---------

Co-authored-by: Andy Butland <abutland73@gmail.com>

src/Umbraco.Core/Notifications/UserPasswordResettingNotification.cs

@@ -0,0 +1,13 @@
+using Umbraco.Cms.Core.Events;
+using Umbraco.Cms.Core.Models.Membership;
+
+namespace Umbraco.Cms.Core.Notifications;
+
+public class UserPasswordResettingNotification :  CancelableObjectNotification<IUser>
+{
+    public UserPasswordResettingNotification(IUser target, EventMessages messages) : base(target, messages)
+    {
+    }
+
+    public IUser User => Target;
+}