Add benchmark code for optimized_transducer and torchaudio.

[csukuangfj]

Usage:

python3 ./benchmark_ot.py
python3 ./benchmark_torchaudio.py

It will generate two folders:

• log/optimized_transducer-30
• log/torchaudio-30

To view the results, run

pip install torch-tb-profiler

and then run

tensorboard --logdir log/torchaudio-30 --port 6006

# open another terminal
tensorboard --logdir log/optimized_transducer-30 --port 6007

Open your browser and go to

• http://localhost:6006/#pytorch_profiler
• http://localhost:6007/#pytorch_profiler

You will see the following results: