Add TfDebug output to the Procedural/Translator

Neither the Procedural nor the Translators make use of the standard TfDebug toolset, which allows fine-grained control over the printed debug messages. Adding debug output would greatly simplify any future debugging.

[The material adapter](https://github.com/Autodesk/arnold-usd/blob/36c113c3d331707b9b68931b32e6d4f018ccb227/render_delegate/material.cpp) and the [Render Delegate debug codes](https://github.com/Autodesk/arnold-usd/blob/36c113c3d331707b9b68931b32e6d4f018ccb227/render_delegate/debug_codes.cpp) are good examples to follow.

Start by reviewing render_delegate/material.cpp and render_delegate/debug_codes.cpp, the examples named in the issue, then locate the Procedural and Translator implementations. Compare their existing debug paths with the TfDebug toolset and verify that the added messages can be controlled through defined debug codes.

Written by the indexing model from the issue text.