Add controlnet module

[xiaoweiw-nv]

The controlnet module uses a TensorRT-optimized controlnet implementation.

Currently, the prompt is read from a file by the text_module and passed to the controlnet_module, the graph looks like:

decode --> controlnet_module ---> encode
      |            ^
      |            |
      -------> text_module

To sync the prompt with the image, the decoder output is also sent to the text_module, once the decoder outputs EOF, the text_module will also generate EOF. However, in the controlnet_module, the propmt_queue is always empty.

To run the pipeline:

python test_controlnet.py

The input image in case you need it:

[xiaoweiw-nv]

Thanks @sfeiwong ! I will merge your modification into the pipeline and push another commit that contains everything.

[xiaoweiw-nv]

@sfeiwong New code pushed, empty queue problem solved, please review.