Viewport Vertex Colors on USDPreviewSurface Using DisplayColors Attribute

[Ziethriel]

Is your feature request related to a problem? Please describe.
As a user I would like to be able to view vertex colors assigned using Apply Color in the viewport when a USDPreviewSurface material is applied.

Describe the solution you'd like
I would like vertex colors to be displayed in an identical manner as if they were applied to a lambert.

[maya-usd-git-sync]

Issue synced internally to EMSUSD-804

[Ziethriel]

Just pinging this to see if this has any momentum. I know it may seem small on your list of things to do, but it's a huge quality of life improvement in my everyday workflow.