Use PhabricatorCachedClassMapQuery in Conduit method lookups
Summary: Ref T11954. Depends on D16994. This implements the Conduit method cache described in that revision for a small global Conduit performance improvement.
Test Plan: Verified Conduit has the same behavior at lower cost. See D16994 for details.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T11954
Differential Revision: https://secure.phabricator.com/D16995