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.

[romayalon]

Some more refactoring ideas based on code review of #8532

1. fork_response_code.NOT_RUNNING is confusing - NC | Online Upgrade | Health CLI update config directory and upgrade checks #8532 (comment)
2. convert multiple used strings to constants - NC | Online Upgrade | Health CLI update config directory and upgrade checks #8532 (comment)