[HYDRA-325] Maya to Hydra renderers do not draw any prims with purposes

[radon199]

Describe the bug Using Storm or any other plugin through Maya to Hydra does not render any prims behind a purpose. It will render prims under default, but not if they are under any other purpose.

Steps to reproduce Steps to reproduce the behavior:

1. Create a USD file with some renderable Prim with the purpose "proxy" or "renderable".
2. See the Prim draw correctly in Viewport 2.0 based on the purpose selection on the ProxyShape
3. Enable Storm or another renderer via Maya to Hydra
4. Prim with purpose will no longer render despite any or all purposes being enabled on the proxy

Expected behavior Prim show draw based on the purposes selected on the ProxyShape

Specs (if applicable):

• CentOs 7
• Maya 2020.3
• maya_usd-0.9.0

[stkrake]

Possible cause and solution outlined here: discussions/2084#discussioncomment-2153701