Blender Git Loki

Viewport: use Filmic without scene exposure/gamma/curves for workbench.

This ignores the scene color managment view settings for solid mode and
lookdev when not using scene lights and world. The scene settings are
intended for tweaking renders and should not affect studio lighting and
matcaps.

There may be cases where a simple sRGB transform is better than Filmic
and we could add configuration for this. Not sure if it really matters
and it may be better if we just assume matcaps and studiolights are all
created for one view transform.

Differential Revision: https://developer.blender.org/D3569