The cluster-wide /storage endpoint lists every storage regardless of
its "nodes" restriction, so _find_default_image_storage (and the
snippet-storage lookup) could pick a storage not actually available on
the node the VM is being created on. On a real server this stranded a
freshly-created VM shell with no disk attached: "qm importdisk" failed
with "storage 'local-lvm' is not available on node 'pve-02'" after the
VM (VMID 103) already existed. Querying /nodes/{node}/storage instead
fixes this, since Proxmox itself only lists what's available there.
Also adds get_image_storages() and an optional storage= override on
create_vm_from_cloud_init, so callers aren't stuck with auto-detection.
Christian Manivong
4d568bc6dc