Adding to components doesn't appear to update component list - show loading indicator

Overview

The component list endpoint is slow (800ms) and when it is loading there is no user feedback.
This is probably ok on first load, but when you add a new code component and are sent back to the layout, it is not evident that the component list is reloading

Steps to reproduce:
* Have a code component
* Add it to code components
* Notice it gets removed from the Code section
* But doesn't show up in code components.... until that finishes loading
* But there is no UI feedback that the list is being refreshed

See video

Proposed resolution

Add a loading indicator when the components list is being refreshed.
Possibly a spinner in the Accordion title?

User interface changes