R1:1f5c54c35a1a

Conduit API: allow phriction.edit to modify viewPolicy and editPolicy

Summary: Closes T15858

Test Plan: See T15858

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

Subscribers: avivey, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15858

Differential Revision: https://we.phorge.it/D25693