Remove Fairchem Legacy. #465
Description
Fairchem legacy was maintained to allow use of models derived from GemNet-OC. When such models are implemented in fairchem v2 we will delete fairchem legacy to reduce maintenance burden. This relates to effort to upstream fairchem v2 interface to fairchem (see #431, facebookresearch/fairchem#1764)
Progress on GemNet-OC described in these issues:
facebookresearch/fairchem#1288
facebookresearch/fairchem#1817