dpif-netlink: break out code to add compat and non-compat vports

dpif-netlink: break out code to add compat and non-compat vports

The vport type for adding tunnels is now compatibility code and any new features
from tunnels must configure the tunnel as an interface using the tunnel metadata
support.

In order to be able to add those tunnels, we need to add code to create the
tunnels and add them as NETDEV vports. And when there is no support to create
them, we need to use the compatibility code and add them as tunnel vports.

When removing those tunnels, we need to remove the interfaces as well, and
detecting the right type might be important, at least to distinguish the tunnel
vports that we should remove and the interfaces that we shouldn't.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@redhat.com>