Menu config screen improvements

[colemanw]

Overview

Live-updates to the menubar when adding/editing menu items on the admin screen.
Adds links to related settings pages to reduce confusion about how to configure various aspects of the menubar.
Fixes broken icon picker and missing Civi icon.

Before

• Missing Civi icon
• Broken icon picker for menu items.
• Yellow alert appears with a "refresh page" link.
• No links to related menu settings.

After

• Fixed Civi icon
• Fixed menu item icon picker
• Live refresh of menubar, no need for yellow alert.
• Added some links to related settings.

[civibot]

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[eileenmcnaughton]

This really just affects the one page. I gave it a spin & it seemed to work well. Merging