Configurable Infiniband port_guid/node_guid

[stgraber]

To make using Infiniband devices more consistent especially when SR-IOV is in the mix, we should be adding two new properties:

• port_guid
• node_guid

When set, Incus will then record the current values into volatile keys (like we do with MAC addresses), set the new values in place and then when the instance is stopped, it will restore those values.

[stgraber]

Forum thread where this was brought up: https://discuss.linuxcontainers.org/t/sriov-infiniband-device-persistent-or-at-least-consistent-port-guid-and-node-guid/20258/7