R1:ab86523ac490

Allow Almanac properties to be deleted, use EditEngine instead of CustomField

Summary:
Fixes T10410. Immediate impact of this is that you can now actually delete properties from Almanac services, devices and bindings.

The meat of the change is switching from CustomField to EditEngine for most of the actual editing logic. CustomField creates a lot of problems with using EditEngine for everything else (D15326), and weird, hard-to-resolve bugs like this one (not being able to delete stuff).

Using…