Summary: Adding class templates to `PhabricatorPolicyAwareQuery` and `PhabricatorCursorPagedPolicyAwareQuery` to make `execute()` have the right return signature, when the query classes are also annotated. Otherwise, the return type is inferred as `PhabricatorPolicyInterface` as before. Test Plan: Add some annotations to query classes and see that `$query->execute()` infers the more specific return type. Diviner still works after ./bin/diviner generate. For example this page still exist: /book/dev/class/PhabricatorCursorPagedPolicyAwareQuery/ And the method newResultObject() is now documented with the return type R|null. Reviewers: O1 Blessed Committers, valerio.bozzolan Reviewed By: O1 Blessed Committers, valerio.bozzolan Subscribers: aklapper, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno Differential Revision: https://we.phorge.it/D26037