This was a temporary solution until we had proper HDR displays.
* Auto detect from the display + view transform if they are HDR, and
enable it automatically. This is based on encoding hdr-video in the config.
* If a HDR transform is selected and there is no HDR display support, an
info message will be shown in the color management panel.
* It is now possible to view HDR images in the image editor, without
needing to use "View as Render".
* There is no versioning to switch to a HDR display, because that also
affects image saving. So users will have to manually select the
"Rec.2100 PQ" display to see HDR colors again.
Ref #144911
Pull Request: https://projects.blender.org/blender/blender/pulls/144565
b0d52c528b