[RFE] bifrost does not assign IP to BMCs

[aeva black]

If one is only provided with a list of BMC MAC addresses and credentials, bifrost can not enroll the hardware in Ironic, because ironic requires the BMCs to have IP addresses.

I propose to add a new role and a playbook to bifrost that will install isc-dhcpd and configure it for static IP address assignment to the set of all MAC addresses. This will use an ansible environment variable "BMCS" which can be read from a file, that will have, at a minimum, the following structure:

BMCS:
  - { name: "foo-server", mac: "aa:bb:cc:dd:ee:ff", ip: "xx.xx.xx.xx" }

This will be used to generate the isc-dhcp config file, to match the server with the BMC IP address that ironic-inspector detects, and later to assign the hostname when bifrost deploys an image to it.