Refactor the landing page backend API and add the top-loved dataset.

[GspikeHalo]

Purpose:

Refactor the backend API of the landing page to reduce duplicate code. Add a top section on the landing page for the newly added dataset categories in the hub.

Changes:

1. Rename getTopLovedWorkflows to getTops and modify its return type to List[DashboardClickableFileEntry] (which is a type included in the search results).
2. Enhance getTops to dynamically select tables and columns, enabling support for different entity types and activities.
3. Refactor fetchDashboardWorkflowsByWids to reuse existing logic in WorkflowResource.scala.
4. Add fetchDashboardDatasetsByDids to reuse existing logic in DatasetResource.scala.
5. Refactor data processing methods in the landing page to reuse search result processing methods (to be replaced during future search-related refactoring).
6. Add dynamic navigation in the browse-section based on user permissions to ensure consistency with list item behavior.
7. Add a "Top Loved Dataset" section to the landing page.

Demos:

"Top Loved Dataset" section:

Redirect when user has access：

Redirect when user lacks access:

[aglinxinyuan]

LGTM!