Make XHPAST unit test "expect" blocks stable and human-readable
This intentionally breaks most tests since it just has the new "expect" generator; the next change will fix them by swapping the test bodies.
Test Plan: Ran "arc unit --everything" after the next change (which fixes all the tests), got a clean build. This change on its own fails all existing XHPAST tests since the block formats don't match.
Maniphest Tasks: T13492
Differential Revision: https://secure.phabricator.com/D21065