Loading sharded model in `tf` from pytorch checkpoints
### System Info

```shell
- `transformers` version: 4.20.0.dev0
- Platform: macOS-12.4-arm64-arm-64bit
- Python version: 3.9.12
- Huggingface_hub version: 0.6.0
- PyTorch version (GPU?): 1.13.0.dev20220521 (False)
- Tensorflow version (GPU?): 2.9.0 (True)
- Flax version (CPU?/GPU?/TPU?): 0.4.2 (cpu)
- Jax version: 0.3.6
- JaxLib version: 0.3.5
```


### Who can help?

@LysandreJik I am not sure who to ping on that 😅 

Loading a big model from the hub in tensorflow is impossible if the model is sharded. 




### Information

- [ ] The official example scripts
- [ ] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [ ] My own task or dataset (give details below)

### Reproduction



```python
>>> tf_model = TFOPTModel.from_pretrained("facebook/opt-13b",from_pt = True)
```
```python 
Traceback (most recent call last):
  File "/home/arthur_huggingface_co/transformers/src/transformers/modeling_tf_utils.py", line 1789, in from_pretrained
    resolved_archive_file = cached_path(
  File "/home/arthur_huggingface_co/transformers/src/transformers/utils/hub.py", line 282, in cached_path
    output_path = get_from_cache(
  File "/home/arthur_huggingface_co/transformers/src/transformers/utils/hub.py", line 486, in get_from_cache
    _raise_for_status(r)
  File "/home/arthur_huggingface_co/transformers/src/transformers/utils/hub.py", line 409, in _raise_for_status
    raise EntryNotFoundError(f"404 Client Error: Entry Not Found for url: {request.url}")
transformers.utils.hub.EntryNotFoundError: 404 Client Error: Entry Not Found for url: https://huggingface.co/facebook/opt-13b/resolve/main/pytorch_model.bin

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/arthur_huggingface_co/transformers/src/transformers/modeling_tf_utils.py", line 1833, in from_pretrained
    raise EnvironmentError(
OSError: facebook/opt-13b does not appear to have a file named pytorch_model.bin.
```

The following script has to be used in order to convert the weights: 
```python 
path = "facebook/opt-13b"
pt_model = OPTModel.from_pretrained(path)
pt_model.save_pretrained(path,max_shard_size = "1000GB")
tf_model = TFOPTModel.from_pretrained(path,from_pt = True)
tf_model.save_pretrained(path,save_config=False)
``` 

### Expected behavior

```shell
Automatically do this in background?
```

Indeed, nice catch! Putting @sgugger in the loop<|||||>Simple reproducer:
```py
from transformers import TFBertModel

model = TFBertModel.from_pretrained("sgugger/bert-sharded")
```<|||||>Putting it on my TODO (might take a few weeks as I have more urgent items, and we don't have a good solution on the TF side for large models right now anyway).<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.<|||||>Fixing this 😄 <|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.