Have EditEngine API methods provide the correct application to Conduit

Summary:
Fixes T9799. Currently, if you can't see an application like Paste, we fatal when trying to generate a result for conduit.query, because the new EditEngine-based paste.edit method doesn't "know" that it's a "Paste" method.

Straighten this out, and use policies and queries a little more correctly/consistently.

Test Plan:

• Called conduit.query as a user who does not have permission to use Paste.
• Before change: fatal.
• After change: results, excluding "paste.*" methods.

Reviewers: chad

Reviewed By: chad

Subscribers: cburroughs

Maniphest Tasks: T9799

Differential Revision: https://secure.phabricator.com/D14492