Background image is not working

[ShinFujieda]

Background image setting does not work in RPR:

However, RPR should have such functionality: https://github.com/GPUOpen-LibrariesAndSDKs/RadeonProRenderSDK/blob/master/RadeonProRender/inc/RadeonProRender_v2.h#L2970-L2986

So it would be better if this can be hooked up in Houdini RPR.