Add date_add, date_upd, soft delete and notification send time

[lmeyer1]

Questions	Answers
Description?	Add fields to the table ps_mailalert_customer_oos, in order for merchant to be able to analyze customer needs and behavior.
Type?	improvement
BC breaks?	no
Deprecations?	no
Fixed ticket?	Fixes PrestaShop/Prestashop#30186. Prerequisite for #28233.
How to test?	Email alerts for customers should just work the same way as before.

There are these improvements in the db:

• when a customer subscribes to an alert, the time is saved to date_add
• when a notification is sent out, the time is saved to notification_sent and the line is soft-deleted.
• the notification is soft deleted on customer request or when a product is deleted
• if the customer requests deletion of his data through gdpr, the email address is anonymized.