Refactor email handling for improved structure

Refactored `Email` and `SendingEmailEvent` to use `record` types, consolidating email-related data into the `Email` class. Updated `SendEmailCommand` to return a `Guid` and simplified mapping logic in `EmailMappingProfile`. Adjusted `SendEmailCommandHandler` to construct `SendingEmailEvent` manually.

Updated `SendingEmailConsumer`, `EmailsController`, and `EmailSender` to reflect the new structure. Removed the old `Email` implementation. Improved logging to reference the `Mail` property.

Revised tests to align with the new structure, ensuring immutability and better separation of concerns.

src/presentation/DigitalData.MessagingService.Client/EmailSender.cs

@@ -125,6 +125,11 @@ public static class EmailSender
             throw new InvalidOperationException("Messaging service is not connected. Call ConnectRabbitMq first.");
 
         var publisher = LazyProvider.Value.GetRequiredService<ISendingEmailPublisher>();
-        publisher.EnqueueAsync(email.ToEvent());
+        publisher.EnqueueAsync(new SendingEmailEvent()
+        {
+            Id = Guid.NewGuid(),
+            Mail = email,
+            QueuedAt = DateTime.Now
+        });
     }
 }