services: virtualization: Export hurd-vm-configuration accessors.

services: virtualization: Export hurd-vm-configuration accessors.

* gnu/services/virtualization.scm (hurd-vm-id, hurd-vm-options): Rename export
to ...
(hurd-vm-configuration-id, hurd-vm-configuration-options): ... these correct
accessor names.
(hurd-vm-configuration?, hurd-vm-configuration-os, hurd-vm-configuration-qemu,
hurd-vm-configuration-image, hurd-vm-configuration-disk-size,
hurd-vm-configuration-memory-size, hurd-vm-configuration-options,
hurd-vm-configuration-id, hurd-vm-configuration-net-options): Export record
predicate and accessors.