[BUG] Only users with advanced page permissions can change page permissions

[jrief]

Description

In CMS3, every user who had the permission page.has_change_permissions_permission(user) was allowed to change the permissions of a page, and optionally their descendants.

In CMS4, the inline view to change the page permissions moved into the advanced page settings view and now is only allowed to users with permission page.has_advanced_settings_permission(user).

This is incompatible behaviour which creates a lot of trouble for us.

Steps to reproduce

• Login in as user with change page permissions on a certain page but w/o advanced page permissions.
• In the CMS toolbar, start editing the current page.
• In the dropdown menu, the "Advanced settings…" item is greyed out and hence he's unable to edit the page permissions.

Expected behaviour

As in CMS3.

Do you want to help fix this issue?

• Yes, I want to help fix this issue and I will join #workgroup-pr-review on Slack to confirm with the community that a PR is welcome.
• No, I only want to report the issue.

In my private repository, there is a patch which can be used to start a discussion on how to fix this.

[fsbraun]

@Aiky30 Do you remember, why this was changed?

I can imagine the following scenarios:

1. Move the permissions to the regular settings form and only show them if the user has the right to change them. (Bloats the regular settings and interferes with the page content separation from page.)
2. Allow both users with page.has_advanced_settings_permission and with page.has_change_permissions_permission to open advanced settings and only show/change the relevant sections.
3. Have a separate permissions form (just as in v3).