R1:536c606ddef3

Implment ApplicationTransaction grouping rules

Summary: Ref T4266. This implements rules similar to the old rules. With D7842, maybe this is reasonable? I think it's not like grotesquely bad, at least.

Test Plan: See screenshot.

Reviewers: chad, wrotte

Reviewed By: chad

CC: aran

Maniphest Tasks: T4266

Differential Revision: https://secure.phabricator.com/D7843