Add a "lock task" button to maniphest tasks
Maniphest Tasks: T125104
I've overhauled the UI and thoroughly tested everything. I think it's ready to go.
Created a regular task, saw that it was publically viewable. Clicked escalate then submitted the form.
Saw that task is now protected with the appropriate view policy and has Security project added.
Subscribers: epriestley, csteipp
Differential Revision: https://phabricator.wikimedia.org/D113