Implement "replace" transactions in Pholio without "applyInitialEffects"

Summary:
Depends on D19923. Ref T11351. Currently, this transaction takes an Image as the newValue and uses some magic to reduce it into PHIDs by the time we're done.

This creates some problems today where I'd like to get rid of applyInitialEffects for MFA code. In the future, it creates a problem becuase there's no way to pass an entire Image object over the API.

Instead, create the Image first, then just provide the PHID. This is generally simpler, will work well with the API in the future, and stops us from needing any applyInitialEffects stuff.

Test Plan: Replaced images in a Pholio mock.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T11351

Differential Revision: https://secure.phabricator.com/D19924