Context: https://linear.app/comm/issue/ENG-2127/
We want to make sure that the payload we get from the REHYDRATE action has all the keys that we expect.
In this diff we add a check to redux-setup:reducer(...) for staff/developers that pulls the keys out of the REHYDRATE payload and makes sure that it matches what we expect (keys in defaultState MINUS those in persistConfig.blacklist)