nm_platform_ip4_address_sync() tries to apply the new configuration
with the minimum effort and doesn't delete addresses if they are
already present on the interface. This can break the ordering, as an
existing address would be promoted by kernel to primary, even if it
was last in our configuration.

Add some logic to ensure the correct order of addresses is always
enforced. This fixes situations like:

 # nmcli connection add type ethernet ifname eth0 con-name t \
                        ipv4.method manual \
                        ipv4.addresses "1.1.1.1/24,1.1.1.2/24,1.1.1.5/24"
 # nmcli connection up t

  => addresses are applied in the right order:
     inet 1.1.1.1/24 brd 1.1.1.255 scope global eth0
     inet 1.1.1.2/24 brd 1.1.1.255 scope global secondary eth0
     inet 1.1.1.5/24 brd 1.1.1.255 scope global secondary eth0

 # nmcli connection mod t ipv4.addresses "1.1.1.5/24,1.1.1.2/24,1.1.1.1/24"
 # nmcli device reapply eth0

  => order is wrong:
     inet 1.1.1.2/24 brd 1.1.1.255 scope global eth0
     inet 1.1.1.5/24 brd 1.1.1.255 scope global secondary eth0
     inet 1.1.1.1/24 brd 1.1.1.255 scope global secondary eth0

Co-Authored-By: Thomas Haller <thaller@redhat.com>