This code originally held an array of refs. But these refs were unset
just before sorting leading to errors.
For the fix, I've used a callback ref to add/remove the DOM elements
to/from the array in state. This way there's nothing that could possibly
mutate just before sort.
Any UTs for vector-web layer components or functionality should go here.
This used to contain the UTs for notifications before they got moved to react-sdk.
