R1:029b1b673394

Partially support CustomFields in EditEngine

Summary:
Ref T9132. This isn't perfect, but doesn't break any existing functionality. This stuff works:

- Editing values.
- Reordering fields.
- All builtin field tyepes.

This stuff may not work yet:

- Assigning custom field defaults.
- Some conduit stuff.
- Fully custom fields?
- Locking/hiding fields? Didn't actually test this one.

I'll keep chipping away at that stuff. In some cases, it may be easier to convert all the CustomField apps…