Editor: Allow setting the optional action mask per editor

Instead of just enable actions that were disabled from the beginning you
can no disable optional actions.

Change-Id: I986b8a72523a8aeec9f4ccf76cd4921018ffc003
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/texteditor/texteditoractionhandler.h

@@ -65,6 +65,7 @@ public:
                             uint optionalActions = None,
                             const TextEditorWidgetResolver &resolver = {});
 
+    uint optionalActions() const;
     ~TextEditorActionHandler();
 
 private: