Show summary data as tree structure in explorer. (#8430)

* Show summary data vectors in project explorer for both summary cases and ensembles.
* Enable Drag to be able to drag'n'drop data vector into future summary plot
* Make sure tree is refreshed on reload/replace operations
* Provide case id and ensemble id in drag/drop object in addition to address

ApplicationExeCode/Resources/ResInsight.qrc

@@ -240,6 +240,7 @@
         <file>ComboBoxDown.svg</file>
         <file>ComboBoxUp.svg</file>
         <file>WellIntAnalysis.png</file>
+		<file>DataVector.png</file>
     </qresource>
     <qresource prefix="/Shader">
         <file>fs_CellFace.glsl</file>