#43619: Display last use date/time for personal access tokens

What does this MR do?

Implements #43619 (moved)

Display last use date/time for personal access tokens

Are there points in the code the reviewer needs to double check?

Does it make sense to throttle the update field?

Migration output

== 20180411120000 AddLastUsedAtToPersonalAccessTokens: migrating ==============
-- add_column(:personal_access_tokens, :last_used_at, :datetime)
   -> 0.0127s
== 20180411120000 AddLastUsedAtToPersonalAccessTokens: migrated (0.0131s) =====

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

#43619 (moved)