neutron: enable nova-event-callback by default

neutron: enable nova-event-callback by default

* Add NovaApiVirtualIP string parameter.
* Compute nova_url and nova_admin_auth_url parameters.
* Configure in Hiera neutron::server::notifications::* parameters.
* non-ha: include ::neutron::server::notifications
* ha: include ::neutron::server::notifications and create orchestration
* Set vif_plugging_is_fatal to True so we actually fail if Neutron is not
  able to create the VIF during Nova server creation workflow.

Depends-On: I21dc10396e92906eab4651c318aa2ee62a8e03c7
Change-Id: I02e41f87404e0030d488476680af2f6d45af94ff