Show `email_reset_offered_at` to admin users

What does this MR do and why?

Allow admin users to see if a user has reset their email or not through the Account email verification process

Related issues:

• gitlab-com/support/support-team-meta#5669 (comment 1661320749)
• 16.3 Support Readiness - (Aug 16 release) Requi... (gitlab-com/support/support-team-meta#5359 - closed)

Screenshots or screen recordings

For Admin area:

Before	After

How to set up and validate locally

1. Create a new user
2. View the admin area for the user profile. Eg. http://<gitlab-instance-domain>/admin/users/<myusername>. There should now be a Email reset done at row with a value of Never.
3. View the API for that user. Eg. http://<gitlab-instance-domain>/api/v4/users?search=<myusername>. There should be a email_reset_offered_at item with a value of null.
4. Open up the rails console, and run the following (Assume the ID of the user we created is 13):

   user = User.find(13)
   user.email_reset_offered_at = 1.hour.ago
   user.save!

5. View the admin area for the user profile. Eg. http://<gitlab-instance-domain>/admin/users/<myusername>. There should now be a Email reset done at row with a timestamp from an hour ago.
6. View the API for that user. Eg. http://<gitlab-instance-domain>/api/v4/users?search=<myusername>. There should be a email_reset_offered_at item with a timestamp from an hour ago.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.