Remove "arcanist project" controllers

Summary: Ref T7603. Ref T7604. There is no need for these controllers anymore as the "Arcanist Project" data is not used anywhere. Depends on D12894 and D12898.

Test Plan: Went to /repository/project/edit/2/ and got a 404.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7603, T7604

Differential Revision: https://secure.phabricator.com/D12897