Add an option to control log output

Detailed description of the requested feature

As of today, the logger prints either to std::cerr (error, warning) or std::cout (info, debug, ...):
https://github.com/NVIDIA/TensorRT-Edge-LLM/blob/8fe7fe102ee0644b02dfc69afc64ff178101cdae/cpp/common/logger.h#L102

There is no option to control the sink to disabled all logs, to log all to std cerr, to log all to std cout.
I would propose to add an environment variable to control the sink output eg:
TRTELLM_LOG_OUTPUT = cerr|cout|null

Timeline

As today this is a blocker because when the user does not want to show any log to end users while being able to redirect to an internal encrypted log.

Describe alternatives you've considered

• redirecting the output (1|2 > /dev/null) but that is not an option when delivering a sdk/library, not an executable.
• a log callback: this will be the best option and open to implement it if you are interested

Best

Read cpp/common/logger.h around line 102 to understand the current std::cerr and std::cout routing. Implement and verify the requested TRTELLM_LOG_OUTPUT behavior for cerr, cout, and null, with logging disabled or directed to the selected stream as specified.