Cascade DarkConsole query plan analyzer to Ajax requests

Summary: Fixes T4123. If you click "Profile" on a page, we already profile all the ajax requests it generates. Do the same for "Analyze Query Plans".

Test Plan: Viewed a page with Ajax requests using "Analyze Query Plans", and not using "Analyze Query Plans".

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4123

Differential Revision: https://secure.phabricator.com/D7601