10598 loader: implement map-vdisk and unmap-vdisk commands

ok lsdev
fd devices:
    fd0:   BIOS drive A (2880 X 512):
disk devices:
    disk0:   BIOS drive C (41943040 X 512):
      disk0p1: EFI
      disk0p2: illumos ZFS
      disk0p9: Reserved
    disk1:   BIOS drive D (41943040 X 512):
      disk1p1: EFI
      disk1p2: illumos ZFS
      disk1p9: Reserved
    disk2:   BIOS drive E (41943040 X 512):
      disk2p1: EFI
      disk2p2: illumos ZFS
      disk2p9: Reserved
    disk3:   BIOS drive F (41943040 X 512):
      disk3p1: illumos ZFS
      disk3p9: Reserved
    disk4:   BIOS drive G (41943040 X 512):
      disk4: ISO9660
zfs devices:
    zfs:rpool
    zfs:rpool1
ok map-vdisk /OpenIndiana_Text_X86.usb
ok lsdev -v
fd devices:
    fd0:   BIOS drive A (2880 X 512):
disk devices:
    disk0:   BIOS drive C (41943040 X 512):
      disk0p1: EFI                 256MB
      disk0p2: illumos ZFS         19GB
      disk0p9: Reserved            8192KB
    disk1:   BIOS drive D (41943040 X 512):
      disk1p1: EFI                 256MB
      disk1p2: illumos ZFS         19GB
      disk1p9: Reserved            8192KB
    disk2:   BIOS drive E (41943040 X 512):
      disk2p1: EFI                 256MB
      disk2p2: illumos ZFS         19GB
      disk2p9: Reserved            8192KB
    disk3:   BIOS drive F (41943040 X 512):
      disk3p1: illumos ZFS         19GB
      disk3p9: Reserved            8192KB
    disk4:   BIOS drive G (41943040 X 512):
      disk4: ISO9660               20GB
vdisk devices:
  /OpenIndiana_Text_X86.usb
    vdisk0:    1719987 X 512 blocks
      vdisk0p1: EFI                34MB
      vdisk0p2: boot               1024KB
      vdisk0p3: illumos UFS        796MB
      vdisk0p9: Reserved           8192KB               
zfs devices:
  pool: rpool
bootfs: rpool/ROOT/openindiana-2019:03:26
config:

        NAME STATE
        rpool ONLINE
          mirror ONLINE
            c2t2d0s1 ONLINE
            c2t1d0s1 ONLINE

  pool: rpool1
bootfs: rpool1/ROOT/gate-56
config:

        NAME STATE
        rpool1 ONLINE
          c5t3d0s1 ONLINE
ok ls vdisk0p3:
vdisk0p3:/
 d  lost+found
    .catalog
 d  .cdrom
    .image_info
    .livecd-cdrom-content
    .volsetid
 ?  bin
 d  boot
 d  dev
 d  devices
 d  export
 d  home
 d  jack
 d  mnt
 d  platform
 d  proc
    reconfigure
 d  root
 d  save
    solaris.zlib
    solarismisc.zlib
 d  system
 d  tmp
ok unmap-vdisk vdisk0:
vdisk0: (/OpenIndiana_Text_X86.usb) unmapped
ok lsdev
fd devices:
    fd0:   BIOS drive A (2880 X 512):
disk devices:
    disk0:   BIOS drive C (41943040 X 512):
      disk0p1: EFI
      disk0p2: illumos ZFS
      disk0p9: Reserved
    disk1:   BIOS drive D (41943040 X 512):
      disk1p1: EFI
      disk1p2: illumos ZFS
      disk1p9: Reserved
    disk2:   BIOS drive E (41943040 X 512):
      disk2p1: EFI
      disk2p2: illumos ZFS
      disk2p9: Reserved
    disk3:   BIOS drive F (41943040 X 512):
      disk3p1: illumos ZFS
      disk3p9: Reserved
    disk4:   BIOS drive G (41943040 X 512):
      disk4: ISO9660
zfs devices:
    zfs:rpool
    zfs:rpool1
ok

ok map-vdisk OpenIndiana_Text_X86.usb
ok map-vdisk OpenIndiana_Text_X86.iso
ok lsdev
fd devices:
    fd0:   BIOS drive A (2880 X 512):
disk devices:
    disk0:   BIOS drive C (41943040 X 512):
      disk0p1: EFI
      disk0p2: illumos ZFS
      disk0p9: Reserved
    disk1:   BIOS drive D (41943040 X 512):
      disk1p1: EFI
      disk1p2: illumos ZFS
      disk1p9: Reserved
    disk2:   BIOS drive E (41943040 X 512):
      disk2p1: EFI
      disk2p2: illumos ZFS
      disk2p9: Reserved
    disk3:   BIOS drive F (41943040 X 512):
      disk3p1: illumos ZFS
      disk3p9: Reserved
    disk4:   BIOS drive G (41943040 X 512):
      disk4: ISO9660
vdisk devices:
    vdisk0:    1719987 X 512 blocks
      vdisk0p1: EFI
      vdisk0p2: boot
      vdisk0p3: illumos UFS
      vdisk0p9: Reserved
    vdisk1:    1365076 X 512 blocks                     
      vdisk1: ISO9660
zfs devices:
    zfs:rpool
    zfs:rpool1
ok ls vdisk1:
vdisk1:/
    .catalog
 d  .cdrom
    .image_info
    .livecd-cdrom-content
    .volsetid
    bin
 d  boot
 d  dev
 d  devices
 d  export
 d  home
 d  jack
 d  mnt
 d  platform
 d  proc
    reconfigure
 d  root
 d  save
    solaris.zlib
    solarismisc.zlib
 d  system
 d  tmp
ok