This minor code cleanup commit does the following:
- sets defaults intensity of RTX denoiser to max.
- adds an initialization check of nvafx.
- splits nvafx initialization from channel allocation for better
readibility of the code.
- moves the intensity update from the filter_audio process function
to the plugin update function.
- logs the error code in case nvafx returns an error when running.
(useful for devs; I haven't translated the error codes which are
available in the sdk).