feat(settings): Check for unused data directory

[joshtrichards]

• Resolves: Presense of /var/www/html/data after install to another data folder #3610

Summary

• Checks for unused data/ folder in SERVERROOT
  • Avoids confusion when looking for logs/troubleshooting
• Minor cosmetic adjustments:
  • Moves DataDirectoryProtected check to security section of checks
  • Adds a verbose success message
• Minor code refactoring
  • clearer variable naming
  • formatting

TODO

• Fix test(s) (oops)

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)