Add a progress bar for the total download of shards
# What does this PR do?

This PR adds a feature requested in #22047 and fixes a small bug I encountered while testing it.

**The feature**: a new progress bar is added when loading a sharded checkpoint that gives the overall progress.

**The bug**: when passing along `force_download=True`, the files were not downloaded if cached, because an early return in `cached_file` returned the cached file.

Fixes #22047 
_The documentation is not available anymore as the PR was closed or merged._<|||||>I'm not observing any changes with this branch:

I tried:
```
python -c 'import sys; from transformers import AutoModel; AutoModel.from_pretrained(sys.argv[1], revision="sharded")' t5-11b
```

after deleting the cache and not getting a new overall progress bar. 

Am I doing something wrong or have some wrong dependencies?<|||||>Woops, wrong check for the file being cached. Can you try again?<|||||>It works great! Thank you, Sylvain!

As you can see it moves the outer progress bar with the inner bar, so it doesn't matter how many shards there are as I was concerned with 72 bloom shards.

![snapshot_50](https://user-images.githubusercontent.com/10676103/224163116-03d9ce60-959f-4064-9dd6-8324946cc06b.png)

![snapshot_51](https://user-images.githubusercontent.com/10676103/224163559-c4ce666f-8f15-4d76-89b6-2c6554a9dbb8.png)
