Split out Skillful Nowcasting GAN, MetNet, and PerceiverIO models into own repos about satflow HOT 6 CLOSED

MetNet is being moved to here: https://github.com/openclimatefix/metnet and Skillful Nowcasting here: https://github.com/openclimatefix/skillful_nowcasting

from satflow.

MetNet and Skillful Nowcasting are now pip installable and all moved over. Future development with those models should go in those repos. In #86 I am also removing the duplicate code in SatFlow.

from satflow.

Perceiver is almost entirely moved over too, more just a failing test in the Conv3D upsampler

from satflow.

Also, there will still be PyTorch lightning wrappers in SatFlow, just the underlying model will be stored and developed in those other repos.

from satflow.

openclimatefix/perceiver-pytorch#11 will make Perceiver installable as well, and close this

from satflow.

Closed with #86

from satflow.