Provide a way to configure the host network

[anmazzotti]

Currently there is a lot of dependency on the DHCP lease for each individual host.
Normally hosts should not reboot at all, and when rebooting they should get back the previous address before the lease expires.
This however is not always the case.

Reporting the following problems from a separate discussion:

• kubernetes expects persistent and static IP addresses
• DHCP is seen as single point of failure
• DNS name resolution is problematic in case of DHCP usage - how to access https:// in case the deployment is using dynamic naming and addressing
• Some EDGE devices need to continue to run once NIC is disconnected

One suggestion is to integrate nm-configurator support.
This implies that the user has to prepare beforehand a map of MAC addresses and IPs, so that the elemental-agent may try to invoke nm-configurator maybe? This could be outside of the OSPlugin layer and supported by the agent directly.

Another possibility is to support the CAPI IPAM Provider api, for example the reference implementation.