Previous conversion to scene linear was done in the display transform
shader. Having a separate shader to convert texture to scene linear
allows drawing input textures with different color spaces into a
viewport and apply display transform on all of them.
Currently unused, but is required for !138094. It could also be used
in the future to avoid host-side linearization in the image engine.
Internally it uses a lot of the same logic for shader caching and
binding, but the code is refactored a bit to make it easier to have
a stronger separation in the future if needed.
Ref #138094
Pull Request: https://projects.blender.org/blender/blender/pulls/138308
5b29ba488f