Updated the Action Scheduler implementation to improve flexibility and clarity. Replaced the 'enable_action_scheduler' option with 'enable_as_email_sending' for better specificity. Introduced hook-based checks to selectively enable email scheduling, ensuring compatibility and optimized performance.
* Sending email notifications directly (without Action Scheduler) on user delete action;
* Changed activation handler priority for integration with Action Scheduler
* Added 'fetch_user_id' argument for fetching the necessary user before email sending when Action Scheduler is active.