Resolve "Display last activity and created at datetimes for users"

What does this MR do?

This MR adds 2 columns to the admin/users view. These columns display the date on which a user was created and the date when last a they performed some form of activity on their account.

Before	After

What are the relevant issue numbers?

Closes #43681 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

EE port: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9100