backends/drm: add support for drm color operations

This allows us to offload color operations to KMS, so we could get a complete zero-copy path for example for HDR video -> screen, with tone mapping applied. There are some visual differences when tone mapping gets applied on AMD right now, but this is IMO good enough to merge, and that can be optimized later (be it by optimizing the 3D LUT, or changing the shader to match the KMS hardware).

See the commits for details. The last commit is a bit large, I intend to split it up a bit more though.

This can be tested with https://gitlab.freedesktop.org/hwentland/linux/-/tree/amd-color-pipeline-v7.3, and there's also a branch for Intel in the same repository (which I haven't tested yet though)