Add request confirmation and security logging for major user actions

[azaozz]

This is a follow-up from #43443.

We can extend the methods and functionality added for privacy request to other "major" user actions:

• Lost password notifications.
• Changing email addresses.
• Deleting accounts.

This will form the base for a user security log screen where admins will be able to see notifications, verify requests, and keep track of other user activities.

[danieltj]

Loosely related to #43484 apart from the verify requests bit.

[azaozz]

Replying to danieltj:

Yeah, I was considering adding a comment to #43484, but seems the two enhancements compliment each other. I mean, we can fire a notification when a new action is requested, but should keep "major user requests than need confirmation through emails" as a separate security related feature.