Fix AST-136035: Preserve tree expansion state when severity filter changes

- Capture expanded elements before clearing the model so the snapshot
  is accurate when restoring after refresh
- Pass expand=true for FILTER_CHANGED (keep GET_RESULTS at false) so
  previously expanded group nodes are restored after filtering instead
  of collapsing the entire tree

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: cx-aniket-shinde

checkmarx-ast-eclipse-plugin/src/com/checkmarx/eclipse/views/CheckmarxView.java

@@ -2474,6 +2474,8 @@ private Image findSeverityImage(DisplayModel model) {
 	private void listener(PluginListenerDefinition definition) {
 		switch (definition.getListenerType()) {
 			case FILTER_CHANGED:
+				updateResultsTree(definition.getResutls(), true);
+				break;
 			case GET_RESULTS:
 				updateResultsTree(definition.getResutls(), false);
 				break;
@@ -2496,9 +2498,9 @@ private void updateResultsTree(List<DisplayModel> results, boolean expand) {
 				resultViewComposite.setVisible(false);
 				attackVectorCompositePanel.setVisible(false);
 			}
+			Object[] expanded = resultsTree.getExpandedElements();
 			rootModel.children.clear();
 			rootModel.children.addAll(results);
-			Object[] expanded = resultsTree.getExpandedElements();
 			resultsTree.refresh();
 			if (expand) {
 				Set<String> expandedDMNames = new HashSet<>();