Show latest snapshot while loading camera view

[bubba925]

Currently on the 14 beta 2, when loading a camera view on a mobile connection or spotty wifi it can take some time and the current loading screen is just black. Would prefer the latest snapshot image or something with a loading wheel to know its doing something or see what I need to see in the snapshot and not even have to load the view. This is the current view.

Might be completely unrelated but it also seems like when using Frigate proxy in HA remotely, load times seem much longer.

[hawkeye217]

Thanks for this. I've added a loading indicator in this PR: #11855