Minor UX improvements on menu items

Problem/Motivation

The form elements were close together and could be difficult to tell where the menu links were in large menu structures.

Steps to reproduce

1. Create a large menu system
2. Create a node
3. Provide a menu link for the new node
4. Open a few different menu and menu links

Proposed resolution

Add some additional spacing and coloring between each menu and menu links to make it easier to tell what menu you are in as well as breaking apart the menu links inside a given tree.

Remaining tasks

None, but would love input on adding additional improvements.

User interface changes

Menu form changes.

API changes

None.

Data model changes

None.