Config Readonly Menu UI

When you use Config Read-only, the menu edit page prevents you from reordering menu links.
It should not, because your menu links could all be links stored as content (not as config), thus could all have their weight changed even if config is read-only.

With this module, you'll get back the menu link drag and drop feature, unless there's at least one read-only (config) menu link in the list (for example, a page view whose menu link is configured in the view configuration page). In this case, you can still change the weight of the content menu links, but through a weight field, not through drag and drop (because drag and drop could have to change the weight of some menu links that are stored as config).

This module came out from #2892631: Don't block content menu links reordering