added file_permission in load_dataset
{'login': 'bhavitvyamalik', 'id': 19718818, 'node_id': 'MDQ6VXNlcjE5NzE4ODE4', 'avatar_url': 'https://avatars.githubusercontent.com/u/19718818?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/bhavitvyamalik', 'html_url': 'https://github.com/bhavitvyamalik', 'followers_url': 'https://api.github.com/users/bhavitvyamalik/followers', 'following_url': 'https://api.github.com/users/bhavitvyamalik/following{/other_user}', 'gists_url': 'https://api.github.com/users/bhavitvyamalik/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/bhavitvyamalik/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/bhavitvyamalik/subscriptions', 'organizations_url': 'https://api.github.com/users/bhavitvyamalik/orgs', 'repos_url': 'https://api.github.com/users/bhavitvyamalik/repos', 'events_url': 'https://api.github.com/users/bhavitvyamalik/events{/privacy}', 'received_events_url': 'https://api.github.com/users/bhavitvyamalik/received_events', 'type': 'User', 'site_admin': False}
[]
[]
From offline discussions: we want to make the permissions handling consistent with `transformers`. However from discussion  in https://github.com/huggingface/transformers/pull/11119 it looks like it might not be a good solution to provide this argument. Users should use umask for now, and we'll see how things evolve.

@bhavitvyamalik I'm closing the PR for now if you don't mind
As discussed in #2065 I've added `file_permission` argument in `load_dataset`. 

Added mainly 2 things here:
1) Permission of downloaded datasets when converted to .arrow files  can be changed with argument `file_permission` argument in `load_dataset` (default is 0o644 only)
2) Incase the user uses `map` later on to generate another cache file of dataset, it ensures the permissions of newly generated file are similar to that of` *-train.arrow` file inside cache_dir for that dataset.
{'url': 'https://api.github.com/repos/huggingface/datasets/issues/2198/reactions', 'total_count': 0, '+1': 0, '-1': 0, 'laugh': 0, 'hooray': 0, 'confused': 0, 'heart': 0, 'rocket': 0, 'eyes': 0}
{'url': 'https://api.github.com/repos/huggingface/datasets/pulls/2198', 'html_url': 'https://github.com/huggingface/datasets/pull/2198', 'diff_url': 'https://github.com/huggingface/datasets/pull/2198.diff', 'patch_url': 'https://github.com/huggingface/datasets/pull/2198.patch', 'merged_at': None}