This redoes the management of the integration configuration list to make

use of the dynamic Config Forms list components. This allows us to

define a Delete action, which will delete the configuration and

automatically update the list. This is much easier than going into the

configuration page (assuming the configuration page offers a Delete

button).
This necessitated some changes to the loading of the page. Now, instead

of building the list up-front, we serialize the data for the UI, and

it's passed in through the Config Forms list machinery. While that's

loading, a "Loading integrations" spinner will be displayed, so the list

doesn't look empty.
Further changes will build on this to better construct the popup display.

Tested this in both the admin UI and in the RBCommons Team Admin UI.
Unit tests pass.