Add a rough Quick Search datasource for Phriction documents

Summary:
Depends on D19106. Fixes T5941. Ref T13077. Allows you to find Phriction documents as suggestions from global quick search.

Also supports w to jump to Phriction and w query to query Phriction.

The actual query logic for the datasource may need some tweaking after it collides with reality, but seems to produce fairly reasonable results in local testing against synthetic data.

Test Plan: Searched for "Porcupine Facts", "Travel Companions", and other useful local pages. Searched for w. Searched for w zebra facts.

Maniphest Tasks: T13077, T5941

Differential Revision: https://secure.phabricator.com/D19107