Add REST API to find old user tokens by realm

Customers want to expire old user tokens by the realm they are associated with. See NEXUS-16690

NXRM 3.17.0 added a beta API to delete user tokens (NEXUS-19170), but an admin still has no REST way to find the tokens to delete by age.

There should be a REST endpoint to find user tokens by realm and older than a certain age. return the userid, realm, and created date.

It would be expected the user then uses the response to determine when to call the DELETE API for NEXUS-16690.