DO NOT MERGE YET: Fixes #3843, Action Bar: Secondary navigation tool?

- added an action provider that handles the long click and redirects to secondary default navigation

This would bring back the functionality as it was before, at the expense of loosing the normal long-press functionality.
IMO the Activity is the owner of the most critical piece of information for this action: the navigation target. If we hand this over to the ActionProvider, we unnecessarily create a shared item.
All action items talk back to their creators through a standardized interface, so I cannot see the encapulation violation in that.