- bhyve/vmrun.sh: support passing disk options same as for bhyve(8)
- bhyve/vmrun.sh: pass all existing readable disks to bhyveload(8)
This is done if the installation mode is not requested or auto-detected.
This is useful when a kernel has to be loaded from multiple disks.
For example from a RAID-Z pool or a ZFS pool with multiple top level
vdevs.