SAC-AE

[belerico]

This PR implements a SAC algorithm working with images. It is inspired by https://arxiv.org/abs/1910.01741

• [x] Main algo
• [x] Sample next obs without saving them
• [x] MemoryMappedReplayBuffer
• [x] Custom CNN and DeCNN
• [x] Reconstruction loss with Variational AutoEncoder

[belerico]

I've trained a Walker-Walk agent with the following:

PYOPENGL_PLATFORM="" MUJOCO_GL=osmesa CUDA_VISIBLE_DEVICES="2,3" lightning run model --devices=2 --accelerator=gpu sheeprl.py sac_pixel_continuous --env_id=dmc_walker_walk --action_repeat=2 --capture_video --sample_next_obs --checkpoint_every=50000 --seed=1

obtaining: