Explorer: added styling for nodes at root

 of workspace

Added a tabbing for the child nodes of a root, to have a visual
difference and avoid confusion

packages/filesystem/src/browser/file-tree/file-tree-widget.tsx

@@ -317,6 +317,6 @@ export class FileTreeWidget extends CompressedTreeWidget {
 
     protected override getDepthPadding(depth: number): number {
         // add additional depth so file nodes are rendered with padding in relation to the top level root node.
-        return (depth + 1) * this.props.leftPadding;
+        return super.getDepthPadding(depth + 1);
     }
 }