Summary:
Aggregate multiple add/remove transactions so we don't restore removed projects for a (remove + add) batch edit.
(Possibly we should do this in the TransactionEditor as well / instead, but it's fairly easy here and this is the only possible case currently.)
Test Plan: Performed a remove + add batch edit without issues.
Reviewers: btrahan
Reviewed By: btrahan
CC: cpiro, aran, epriestley
Maniphest Tasks: T985
Differential Revision: https://secure.phabricator.com/D1967
81be1cf27b