Studio: revising static course outline reference template

* static markup for all section states in outline UI
* static markup for all subsection states in outline UI
* static markup for all unit states in outline UI
Studio: styling revamped course outline-related UI

* adding in outline-related color values
* styling for publishing states
* light styling abstraction for specific outline and unit/container contexts
* revising add item to outline button styles
* adding a few bells and whistles (hover states and error pulsing)