Currently it is not possible to view the vertex colors of an object. To optimize the workflow, workbench will need to support Vertex Colors. The Vertex Colors is a new option in `shading->color_type`. When objects do not have vertex color, the objects will be rendered with the `V3D_SHADING_OBJECT_COLOR`. In order to support vertex colors in workbench the current texture/solid shading structure is migrated to a primary shaders and fallback shaders. Fix: T57000 Reviewers: brecht, fclem Differential Revision: https://developer.blender.org/D4694