Add support for /auth-check

[Wauplin]

Related to huggingface/datasets#7110.

We have a endpoint to check a given user/token has access to a repo: GET /api/{repo_type}s/{repo_id}/auth-check". It's especially useful to check permissions on a gated repo. Let's add a auth_check method to HfApi based on datasets implementation:

def check_auth(hf_api, repo_id, token=None):
    headers = hf_api._build_hf_headers(token=token)
    path = f"{hf_api.endpoint}/api/datasets/{repo_id}/auth-check"
    r = get_session().get(path, headers=headers)
    hf_raise_for_status(r)

If the user don't have access, a RepoNotFound or GatedRepoError error should be raised.
Need to add a proper docstring and tests as well.

[Wauplin]

(assigning to @cjfghk5697 see #2444 (comment))

[Wauplin]

Closed by #2497. Thanks @cjfghk5697 !