R1:3f8e5c96209d

Straighten out reorder permissions on form configurations

Summary:
Fixes T10012. The permissions here are little weird: you need edit permission on the //configurations//, not the //engines//. I was checking edit permission on the engines only.

I should possibly make this a bit more consistent, the engine edit permission is just very convenient to use to enforce object create permission right now. I'll likely clean this up after T9789.

Test Plan:
- Tried to reorder forms as a less-privileged user, got…