Add support for ControlNet

[dilithjay]

This PR adds support for the canny2image functionality of ControlNet.

Given an image, ControlNet generates a new image from the canny edges of the original image.

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Reference:

@misc{zhang2023adding,
  title={Adding Conditional Control to Text-to-Image Diffusion Models}, 
  author={Lvmin Zhang and Maneesh Agrawala},
  year={2023},
  eprint={2302.05543},
  archivePrefix={arXiv},
  primaryClass={cs.CV}
}