[DEV] Allow CoreSMD to update SMD when it assigns an ip address

[alexlovelltroy]

CoreSMD supports assigning ip addresses to node via DHCP when it can look those IP addresses up in SMD via the MAC.

Magellan can detect ethernet interfaces through redfish and make them available for lookup in SMD.

What's missing is a piece that allocates ip addresses to interfaces in SMD for coresmd to find.

This issue proposes that coresmd should have a way to assign ip addresses in SMD as part of responding to dhcp requests from known MACs. This doesn't prevent something else from also setting the ip addresses in SMD. Since coresmd refreshes its cache every minute, changes in SMD will be picked up quickly.

In order to complete this task:

• Add functionality for coresmd to use a token, supplied at runtime for updating ip addresses in SMD. This functionality should also include refreshing the token periodically.
• Add API calls that set the IP address of an interface in SMD without blocking DHCP responses to nodes.