Move "Archive Project" to a standard, separate action

Summary:
Ref T4379. Projects currently include their "delete/disable" function as part of edit, which is atypical. Instead, provide it as a first-class action. This is primarily for consistency between applications.

(The action list on projects is getting pretty huge, but we can deal with that separately; I have some ideas.)

Test Plan: Archived/unarchived a project. Edited a project.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4379

Differential Revision: https://secure.phabricator.com/D8177