Summary:
Ref T418. This is fairly messy, but basically:
- Add a validation phase to TransactionEditor.
- Add a validation phase to CustomField.
- Bring it to StandardField.
- Add validation logic for the int field.
- Provide support in related classes.
Test Plan: See screenshot.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T418
Differential Revision: https://secure.phabricator.com/D7028
