Extend admin Permissions to be specific to the document-level

[jmikrut]

Right now, Payload's Admin UI permissions are calculated only when a user changes within the admin UI.

This can present problems and make access control a bit harder to understand:

• Access control functions gets called when they are not supposed to #575
• Access control: read at field level not working properly #1369
• Delete button stays visible when access is query based #1375

If your access control functions rely on doc-based data to calculate which fields are able to be read / edited / updated, the admin UI will not reflect these changes. The access control functions will still work, however, the UI may not respond as you might expect.

We need to extend how permissions are calculated to include a layer that runs on the document level, which will improve the way that the admin UI responds to access control.

The way to do this is to extend our built-in /access operation so that it can take context or similar - where you can pass a document ID or a global slug, and the access will be run against that specific document or global.