Add extra Ironic instance_info metadata

Ironic currently only sets instance_info/instance_uuid, we want to expand this to include project_id, user_id and flavor name, such that we are more consistent with what is set in Libvirt guest metadata. All of these fields are deleted when a node is undeployed, similar to instance_uuid today. The project_id might in the future be used to help with Ironic API RBAC.

(We would like this to be a specless blueprint).