DataSource: add code to assign & display new raster thumbnail Icons for search results list
Data source icons in the Data search-results list are currently rendered badly (the display is trying to render a small version of the vector icon defined in DataSourceIcon.java). Instead, need to do 2 things:
1) add code to make the system assign raster thumbnail icons to the list entries - see Bug #2362. These "actors' currently do not get the new svg or raster icons assigned, because they are not instantiated via ActorMetadata.java, where the icon-assignment code is.
2) Change the list display code so it looks for and renders the raster icons instead of the default ptii one. Not sure where the code is to do this, since I haven't looked yet, but I'm guessing it might require digging deep...