Add a "Restore missing Menus" to admin UI

First of all, I like the new organization of the admin UI.

I don't love that dragging a menu item to the favorites area removes it from it's natural habitat.

Because, when I delete it from the favorites area, it's not anywhere in the menu anymore. I was shown a non-obvious way to get it back (click and hold on some existing menu item until the search box shows up, then type the name of the missing item in).

I'd love a couple of changes:

1. Make the drag to favorites a copy, rather than a move.
2. Add a "reset menus", "restore deleted menu items" or make menu editing a bit more discoverable.