CLI command to move cache folder

[Wauplin]

From #1564 (comment):

If I understand correctly, a simple CLI command to move the cache from one path to another would be great for some users?

cc @vladmandic

The simplest version would be to copy only the blobs/ folder and symlinks will be resolved at runtime. Creating the snapshots/ and refs/ folders might be more error-prone especially on Windows. It shouldn't be problematic as the first time the user call hf_hub_download, they would be recreated.

Also would be good to add a warning: "Make sure to update your $HF_HOME environment variable."