Handle SSH generated keys in Conduit passphrase.query
Summary: Fixes T6601
Test Plan: echo '{"ids":["71"],"needPublicKeys":true,"needSecrets":false}' | arc call-conduit passphrase.query
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: epriestley
Maniphest Tasks: T6601
Differential Revision: https://secure.phabricator.com/D10885