HostRebootMixin declares reboot_host(), mixed into DeviceTypeDriver so
any device may be restartable. netOrk restarted hosts by sending
/sbin/reboot through a driver's private _send_command; a driver talking
to an API had no such method and the reboot was silently skipped.
HypervisorDriver gains GUEST_AGENT_PACKAGES / GUEST_AGENT_RUNCMD, the
agent cloud-init installs so the hypervisor can read a new VM's IP.
The default stays qemu-guest-agent; VMware declares open-vm-tools.
NetworkTargetDict.kind may be "portgroup": a VMware port group fixes its
VLAN like an SDN vnet does, without being one.
VMDict.vmid and VMConfigDict.vmid were int. Proxmox numbers its guests,
but VMware identifies a VM by UUID, which an int cannot hold. The
provisioning dicts already carried vmid as a string; the read side now
matches. Proxmox reports "100".
VMConfigDict gains optional hardware details -- os_name, cpu_type,
sockets, cores_per_socket, firmware, machine and passthrough (PCI/USB,
as VMPassthroughDict) -- so netOrk's VM hardware view can be filled by
any hypervisor instead of reading Proxmox's raw config through the
driver's private API.
Also fixes the README's hypervisor example, which still named the
pre-contract snapshot_create.
BREAKING CHANGE: VMDict.vmid and VMConfigDict.vmid are str.