Refactor most uses of AphrontFormDateControl to user AphrontFormDateControlValue
Summary: Ref T8024, Refactor most uses of AphrontFormDateControl to user AphrontFormDateControlValue
Test Plan: Countdown and Phrequent should now save form data in error state.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T8024
Differential Revision: https://secure.phabricator.com/D12731