tabular mapping: Add map thumbnail on Dataset page

[raprasad]

If a tabular DataFile has an associated "MapLayerMetadata" object:

1. Retrieve a thumbnail from WorldMap.

   • Already happens for shapefiles
   • Code is here:
     • File/Method: MapLayerMetadataServiceBean.java retrieveMapImageForIcon

2. Display the thumbnail on the:

   1. Dataset page within the file listing
   2. File Page
   3. Dataverse search result card

3. Under the thumbnail, display a "Preview link" which pops up a modal window showing the map

Current

Expected