DRAFT - Make cancel/reinstate child/ghost/recurring events work

Summary: Ref T2896, Make cancel/reinstate child/ghost/recurring events work

Test Plan: Cancel/reinstate child/ghost/recurring events.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T2896

Differential Revision: https://secure.phabricator.com/D13145