NC | Health CLI refactoring ideas

[romayalon]

Environment info

• NooBaa Version: master
• Platform: NC

Refactoring Suggestion

1. Add validation of the config directory.
2. Change the response to have more informative names, specifically total_fork_count and running_workers caused some confusion in the past.
3. Remove error_type when not needed.
4. Check the accessibility of a bucket path by the owner of the bucket - see Acess Denied for S3 buckets is not reporting #8240
5. Add a flag for not checking permissions.
6. Add an account/bucket schema validation (currently it's just a json schema check).
7. rename MISSING_CONFIG error, this name does not fit because we iterate the config directory.
8. add jsdocs.
9. merge is_dir_accessible() and stat() to a single function that handles both.