Provide a more straightforward way to revoke SSH keys by finding and destroying the objects

Summary: Ref T9967

Test Plan:
Ran migrations.
Verified database populated properly with PHIDs (SELECT * FROM auth_sshkey;).
Ran auth.querypublickeys conduit method to see phids show up
Ran bin/remove destroy <phid>.
Viewed the test key was gone.

Reviewers: Blessed Reviewers, epriestley

Reviewed By: Blessed Reviewers, epriestley

Subscribers: Korvin

Maniphest Tasks: T9967

Differential Revision: https://secure.phabricator.com/D14823