Cannot remove missing permissions from post/page

[mikaellindemann]

Ongoing development of a website can obsolete and remove permissions used to protect single pages or posts in Piranha.

Issue

If a permission is removed from the Piranha app, the permissions picker in the page/post settings is no longer available, even though the page/post is protected by said permission.

Therefore it is impossible to remove the required permission, while it still fails the user accessing the page with either Policy not found (in case the cleanup also removed the AspNetCore Authorization Policy, or just unauthorized if the policy is there, but the user does not have it.

Suggested solutions

1. Automatically disregard unknown permissions (potentially on next publish of the page, if it makes it easier with caching and database updates).
2. Show applied permissions in the permission picker, even though they no longer exist in the code. This allows the editor to remove the permission as a requirement for the page.