Provide parent menu item information in the "Menu Links" UI

The current UI for the "Menu Links" configuration page doesn't provide information about parent menu items (other than "--" characters to represent depth). If you have a menu structure where multiple links have the same title, you're forced to use trial and error to locate the correct menu link. This patch navigates the parent items in the menu link array to construct a string that better represents the menu tree.

Example use case would be a menu structure as follows:

-- Home
-- Brands
---- Brand 1
------ News
---- Brand 2
------ News

In this case, your display in the Menu Links section of the Configuration UI will show this:

"main menu: ------ News"
"main menu: ------ News"

With the patch applied, you would instead see:

"main menu: Brands -- Brand 1 -- News"
"main menu: Brands -- Brand 2 -- News"

Patch attached.