Remove PhabricatorProjectEditor

Summary:
Ref T4379. Perform all editing with modern transaction infrastructure. A few practical changes here:

  - Message for "project name required" should be a little nicer. I'll deal with this once more stuff gets straightened out. You get a reasonable message now, it's just not nicely handled as part of the form.
  - Message for "project name is not unique" should be a little nicer. Same as above.
  - Previously, we would automatically archive a project when the last member left or was removed. I'll probably restore this in a bit but am omitting it for the moment for simplicity.
  - Previously, we would create projects with goofy nonsensical permissions. Now we create them with reasonable permissions.

Test Plan:
  - Created project.
  - Edited project.
  - Ran unit tests.
  - Viewed project edit history.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4379

Differential Revision: https://secure.phabricator.com/D8168