Comment 5 for bug 233112

Here's a plan to make it happen. Currently the actions are created by the media_menu_activity.

- In menu_activity we should add the ability for the activity to create an action component given its path (plugin:component_name). Let's name that method: _create_action(path) for instance.
- in media_menu_activity config we can add 2 options:

  * directory_actions: list of strings indicating action paths
  * file_actions: list of strings indicating action paths

- media_menu_activity would use these options, call _create_action for each value of the lists, create menu_models and insert them at the correct places in the menu tree.
- we would need to add additional data (such as the menu label) to the actions