To improve security, operators have asked for two VIPs for
their cloud.
VIP 1 is the internal VIP that can reach internal and admin endpoints.
In addition, the internal VIP can also reach other internal services,
such as the database and message services.
VIP 2 is the external VIP that can only reach public endpoints.
With one VIP only, all services are reached at the same address.
To add a second VIP, this patch adds two new configuration parameters.
kolla_external_vip_address: is an IPv4 address to use for created VIP
kolla_external_vip_interface: is the network interface to use for VIP
In this scenario, the first VIP (the internal VIP), is defined by
the original parameters (kolla_internal address and network_interface).
When using two VIPs, the existing kolla_external_address parameter
should be/point to/resolve to the kolla_external_vip_address.
Closes-bug: 1535333
Change-Id: I5bfcefaf7899298455cdade8209c34324aebfecb
34c2cb8e64