R1:e469f8594ed3

Implement Pholio file add/remove transactions without "applyInitialEffects"

Summary:
Depends on D19924. Ref T11351. Like in D19924, apply these transactions by accepting PHIDs instead of objects so we don't need to juggle the `Image` objects down to PHIDs in `applyInitialEffects`.

(Validation is a little light here for now, but only first-party code can reach this, and you can't violate policies or do anything truly bad even if you could pick values to feed in here.)

Test Plan: Created and edited Mocks…