Move the logic for generating base accounts for a new client from the ClientObserver into a dedicated command class (GenerateBaseAccountCommand). This improves code organization and reusability.
- The command is now used in the ClientObserver::created method.
- The command is also made available as a manual action in the AccountsRelationManager table header, allowing admins to generate base accounts for existing clients that lack them.
- Added necessary imports to the CreateSale page, though the command is not directly used there in this diff, suggesting preparatory work for future integration.
