Pass the new node in ProjectTree::currentNodeChanged

Avoids some roundtrips asking for ProjectTree::currentNode()
which traverses the project tree every time.

Change-Id: I650728eab5a47a7f4760cf88844a4b7106365255
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/cmakeprojectmanager/cmakeprojectplugin.h

@@ -27,6 +27,8 @@
 
 #include <extensionsystem/iplugin.h>
 
+namespace ProjectExplorer { class Node; }
+
 namespace CMakeProjectManager {
 namespace Internal {
 
@@ -60,7 +62,7 @@ private:
     bool initialize(const QStringList &arguments, QString *errorMessage) final;
     void extensionsInitialized() final;
 
-    void updateContextActions();
+    void updateContextActions(ProjectExplorer::Node *node);
 
     class CMakeProjectPluginPrivate *d = nullptr;
 };