[Feature] Add loading indicator or some type of fallback for images that require processing (423)

[colbyfayock]

Feature Request

Is your feature request related to a problem? Please describe.

When using removeBackground with CldImage the server returns a 423 and we try to poll until it's ready, but in the meantime, it shows a broken image

To avoid the broken image, we can show some sort of indicator that it's loading, perhaps a loading animation (though that's opinionated) or perhaps use the original image without the background removed, with a lower opacity, to indicate that it's loading

[colbyfayock]

duplicate #514