Add support for auto-configure network at early boot
We need be able to let the cloud proviers configure the network before
binging it up. Add a set_network_config
action that is run in early
phase.
Default to simply call assemble-interfaces, and add some logic to autodetect which NIC is connected in nocloud provider. This means that if you have multiple ethernets, nocloud will pick the one that is connected (carrier detected) or fallback to the first (usually eth0).