Workbench: add feature for objects with textures to have transparency settings

When using Workbench to render in texture mode, any objects which have a texture applied are no longer affected by color transparency settings. Material -> Viewport display -> color -> alpha has no effect. Moreover, textures with alpha channels render, however the alpha channel is threshold-ed (0 or 1, nothing in between)

It would be nice if the color - alpha value would act as a multiplier after the texture.