Add herald support for Maniphest

Summary:
standing on the shoulders of the badass work to move Maniphest to ApplicationTransactions, this diff implements a few methods and adds an adapter class.

For now, we can add cc and flag tasks. I figure see what people ask for? Ref T1368.

Test Plan: created herald rules for title and description text hits. made tasks and verified CC and flags worked.

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, aran

Maniphest Tasks: T1368, T1638

Differential Revision: https://secure.phabricator.com/D7122