[UX] Make special field items (such as title, language and path alias) available in the "Manage display" tab.

As it is now, their label is shown above the respective form element and there is no way to be hidden or set inline through the UI like the rest of the fields.

This would for example allow the path alias of a specific content type to have a default with tokens and then be hidden from the form so that users cannot change it (even if they have the proper permission to edit the aliases of other content types).