[Child pages] Allow sorting of child pages

[tudoramariei]

🚧 The issue is still a work in progress.

Is your feature request related to a problem? Please describe.
When adding new pages as children to a page, the order can't be set, and there isn't a consistent way in which the order changes.

Describe the solution you'd like
When a page has child pages (a page has set it as a parent page), sorting the child pages in the admin interface should be possible.

Describe alternatives you've considered
In other places, items are ordered based on the last edited date.
At least this way of ordering items could be implemented so a framework for ordering exists and a way for users to edit items.

Additional context
We would need a design and/or workflow for this to know how these changes should look like.