NCNet-flax

Unofficial implementation of NCNet using flax and jax.
Paper: https://arxiv.org/abs/2208.11609
Official code(tensorflow2, pytorch): https://github.com/Algolzw/NCNet

TODO:

• Implement NCNet
• Implement training code(Using Div2K dataset in tfds)
• Implement tensorflow lite conversion(quantization) and evaluation code(on Set5)