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)
Studio: outline UI styling revisions

* sync up stateful class names
* show status border/visual for subsections in collapsed and expanded states
* hide new-centric actions and messages on collapsed items
* show/hide content elements for outline containers based on collapsed states
* button-new semantic changes and icon-padding visual tweaks
* replaced draft-like icon to something not used for actions