Add optional color to debug groups/markers

[JMS55]

Is your feature request related to a problem? Please describe. A program with thousands of API calls gets hard to debug in tools like NSight, RenderDoc, or PIX.

Describe the solution you'd like Allow optionally specifying a color for debug group/marker functions to make visually finding the passes your interested in easier.

[cwfitzgerald]

Amusingly, this used to be in the api way long ago but was removed. I think we should just ignore any color values unsupported by the underlying api.

[JMS55]

Agreed, if the underlying API does not support it, just skip the coloring.