Extend the debug output of the Render Delegate

The Render Delegate should utilize the TfDebug utilities and print information about receiving invalid data and extend it's currently used debug codes.

[The material adapter already makes use of TfDebug](https://github.com/Autodesk/arnold-usd/blob/36c113c3d331707b9b68931b32e6d4f018ccb227/render_delegate/material.cpp), and we should follow its example.

Start by reading render delegate sources and compare their current debug handling with the TfDebug usage in material.cpp. Identify how invalid data is received and which debug codes are currently used; done means invalid-data information is reported and the Render Delegate exposes the intended additional codes, with relevant tests or checks passing.

Written by the indexing model from the issue text.