[NEW] Handle mail queue warning and Create admin page for manage mail queues

• [NEW] Handle mail queue warning and create an admin page for managing mail queues

• Create a new preference “Number of retries to send emails when there are errors“ mailer_queue_max_retries with a default value of 10.
• Update the code that picks up emails from the email queue to ignore emails with a retry count bigger than the value in the setting.
• A table with the list of messages in the queue
• A summary of the current mail queue status

Ref: https://avan.tech/item70059