[Feature] Transcode policy for images (e.g. high res for heic only)

I have searched the existing feature requests to make sure this is not a duplicate request. • Yes The feature Last transcoding request I promise 😇. Unfortunately, things are moving in the direction where universal support of image formats cannot be expected, most notably with heic only working in safari. As such, I think it will be useful to refactor server image settings to be more like video (transcoding) settings, but still with thumbnails and previews. A basic use-case: we want low-quality previews for fast browsing. We also want high-quality originals for zooming in. I personally have "prefer originals" enabled and so keep low-quality on the server but usually preview the original assets. However, this breaks down for heic format images. These can't be opened in original format in chrome (etc. except safari), so you are obliged to either (1) use the low-quality previews for zoom or (2) transcode all your heic AND jpeg assets into high-quality previews (…