(stable) Fix "before/after" cursor paging for API call "feed.query"

Summary:
Ref T13266. See https://discourse.phabricator-community.org/t/undefined-method-setafterid-when-calling-feed-query/2653.

This older API call needs an update to the newer paging/cursor API.

Test Plan: Called feed.query with an "after" parameter.

Reviewers: amckinley

Reviewed By: amckinley

Subscribers: Itms

Maniphest Tasks: T13266

Differential Revision: https://secure.phabricator.com/D20456