ACL Token "Last Used" Time

#### Feature Description

It would be very helpful to have some information around when ACL tokens have been used for API access. Specifically when the token as last been used.

#### Use Case(s)

When rotating ACL tokens (and deprecating/deleting an old one), there is no easy way to determine if a token is no longer being used before deleting it. Currently, we are just setting all of the policies on the token to `deny` and hoping nothing breaks. A "LastUsed" time would go a long way to increasing confidence and safety when rotating production-used ACL tokens.