[Feature] Notice related to cache delay following permission update

[fmigneault]

Description

Because cached request access (Twitcher side) could mismatch a recently applied permission (Magpie side) until the cache expires on Twitcher, it can be confusing for an admin to understand why a resource that just received the proper permissions for access remains inaccessible for a short duration, and becomes available slightly later (after cache expired).

Solution

• A notice should be displayed as reminder in the UI such that it indicates, following a new/updated/deleted permission, that it could take some time to take effect according to Twitcher cache. Since Magpie doesn't know whether (and how long) the Twitcher caching could be set, it can only indicate it is a possibility.

• Notice about Cache-Control: no-cache header should also be provided (via documentation link).

• Documentation should be added about cache-control header and supported values / resulting behaviour.