Restore "Tags" and "Subscribers" edit capabilities to Maniphest bulk editor

Summary: Depends on D18867. Ref T13025. Fixes T8740. Rebuilds the tag/subscriber actions (add, remove, set) into the bulk editor.

Test Plan: Added, removed and set these values via bulk edit.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13025, T8740

Differential Revision: https://secure.phabricator.com/D18868