Analyzer: Put more common code into the DetailedError* base classes.

Namely:
    - The "copy" action and the corresponding "slot".
    - The context menu.
Plus an infrastructure for adding new common and custom actions.

Change-Id: I4bf8b28b4ad60b4022abbfc0b401c3b832b94560
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/plugins/valgrind/memcheckerrorview.h

@@ -57,11 +57,11 @@ public slots:
     void settingsChanged(ValgrindBaseSettings *settings);
 
 private slots:
-    void contextMenuEvent(QContextMenuEvent *e);
     void suppressError();
 
 private:
-    QAction *m_copyAction;
+    QList<QAction *> customActions() const Q_DECL_OVERRIDE;
+
     QAction *m_suppressAction;
     QString m_defaultSuppFile;
     ValgrindBaseSettings *m_settings;