Migrate project profiles onto projects, and remove ProjectProfile object

Summary:
Ref T4379. Long ago, the "Project" vs "ProjectProfile" split was intended to allow a bunch of special fields on projects without burdening the simple use cases, but CustomField handles that far better and far more generally, and doing this makes using ApplicationTransactions a pain to get right, so get rid of it.

The only remaining field is profileImagePHID, which we can just move to the main Project object. This is custom enough that I think it's reasonable not to express it as a custom field.

Test Plan: Created a project, set profile, edited project, viewed in typeahead, ran migration, verified database results.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4379

Differential Revision: https://secure.phabricator.com/D8183