R1:6d33ba7dc401

Move Diffusion to "withPaths()" for "Recent Open Revisions", and remove "withPath()" from DifferentialRevisionQuery

Summary: Ref T13639. Move Diffusion to use the new API and get rid of the old API now that it no longer has any callers.

Test Plan:
Grepped for remaining callers.

{F8539335}

Maniphest Tasks: T13639

Differential Revision: https://secure.phabricator.com/D21620