R1:e6118bcbaf7d

Tweak application and maniphest editors to handle policy corner cases better

Summary:
Fixes T4362. If you have a default edit + view policy of "no one" things get weird when you try to create a task - basically its impossible.

Ergo, re-jigger how we do policy checks just a bit.

- if its a new object, don't bother with the "can the $actor edit this thing by virtue of having can see / can edit priveleges?" That makes no sense on create.
- add a hook so when doing the "will $actor still be able to edit…