Facet sidebar shifts when it refreshes

[elebitzero]

The issue is as @thadguidry says:

Unneccesary jumping up/down of Facet panels while users click on selections. The div browsing-panel-indicator will quickly show a hidden spinner “Refreshing facets…” which is above the browsing-panel-controls and hence causes all child elements underneath to suddenly move down and then back up. The effect to a user is disconcerting with jerky motion.

[thadguidry]

@elebitzero Thanks for tackling this issue. The question will be where to move this small notice so that users still see it if there is a long running refresh on many facets? I don't even know how to produce such a state. Maybe have many (25-50?) facets with some custom expressions that take a long time to calculate? We also could change the longish test "Refreshing facets..." to just a spinner icon (does Clusterer have one useful to borrow or shrink?) with some alt hover text (so folks can hover on it and know that it is "Refreshing facets...") and place this small icon in the top right or left corner of leftPanelDiv or in lower elements? That way, it could be hidden, and when shown, it wouldn't add a large visible div like now appearing before the facet groups.
https://www.cssscript.com/demo/svg-loading-spinner/
https://github.com/lukehaas/css-loaders