Debugger: Fix regression in "Show in separate Window"

After the tree model changes, the main insertion path did
not trigger the update in the separate Window anymore.

Task-number: QTCREATORBUG-14101
Change-Id: I90d8c0874be473a67c6260ca9bf63099f5d54a06
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/plugins/debugger/watchhandler.cpp

@@ -1177,6 +1177,8 @@ void WatchModel::insertItem(WatchItem *item)
     QTC_ASSERT(parent, return);
     const int row = findInsertPosition(parent->children(), item);
     parent->insertChild(row, item);
+
+    item->walkTree([this](TreeItem *sub) { showEditValue(*static_cast<WatchItem *>(sub)); });
 }
 
 void WatchModel::reexpandItems()