style: add visual divider between folders and items in workspace listing

[ayeshurun]

📥 Pull Request

This PR enhances the fab ls command by adding a visual divider to improve the readability of workspace listings.

✨ Description of new changes

• Visual Divider: A ------------------------------ divider now separates folders from items in the output.
• Conditional Display: The divider only appears when folder_listing_enabled=true, output_format=text, and the --long flag is not used.
• Implementation: The divider is added as a data entry, avoiding changes to core rendering logic.

This change provides a clearer distinction between content types in the workspace, improving user experience for large workspaces.

Example Output

Sales.Folder
Marketing.Folder
Engineering.Folder
------------------------------
Product-Catalog.SemanticModel
Sales-Dashboard.Report
Inventory.SemanticModel
Customer-Data.Report