Implementing Viewport Holdouts on USDs Similar to Holdout Attribute on Geometry

**Issue:**
The current versions of Maya USD doesn't seem to support holdouts in the viewport for USDs in the same way it does for native geometry with the holdout attribute applied. This creates inconsistency in the workflow when using holdouts on USDs in the viewport and is terrible for live action film work, with plate backgrounds.

**Description:**
Typically in Maya, we can use the holdout attribute on geometry to visually occlude other objects in the viewport. However, this functionality is currently lacking for USDs, which is causing issues in our viewport-based workflow.
Implementing the ability for USDs to behave as holdouts in the viewport, similar to standard geometry with the holdout attribute, would be a significant improvement for USD handling in Maya.

**Possible solution**
Having an attribute on the usd object, like in the render stats of normal maya geo, that could turn on and off holdout ability.

Start by reproducing the viewport difference between native Maya geometry with the holdout attribute and a USD object, then inspect how USD objects are integrated into Maya's viewport. Done means a USD object has a way to enable or disable holdout behavior and visually matches native geometry in the live-action plate workflow.

Written by the indexing model from the issue text.