Add `accelerate` support for `ESM`
# What does this PR do?

This PR adds `accelerate` support for `ESM` models, so that the largest `ESM` models (15B params) can be loaded in 8-bit, therefore easing accessibility for large protein models. This also introduces the first protein model that can be loaded in 8bit.
```
# pip install accelerate bitsandbytes
from transformers import AutoModel

model = AutoModel.from_pretrained("acebook/esm2_t48_15B_UR50D", device_map="auto", load_in_8bit=True)
```

cc @sgugger @Rocketknight1 

slow tests pass
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