missing VAE encoder with DWT

@shonenkov Great work everyone!
As far as I can tell, there is only VAE decoder with DWT and no corresponding encoder.
Encoding with get_vae(dwt=True) produces the same number of tokens as get_vae(dwt=False) on the same picture size but they are different. And the DWT decoder doubles the original image size. The result is large but blurry and I see quality loss even after reducing to the original image size. The image decoded-encoded with default VQ GAN model still seems to be better than the DWT model.
@bes-dev Is this due to the need of re-training the model end to end you mentioned in #42 ?
I would expect the compatible VAE DWT encoder encode 512x512 image into 1024 tokens and the decoder restore the image back to 512x512.
I think for now VAE with DWT needs 256x256 image prompts rather than 512x512 but then the resulting quality is unfortunately not worth the effort. Looking forward to see DALL-E trained end-to-end on 512 images.