Fix column alignment with long zpool names

Fix column alignment with long zpool names

`zpool status` normally aligns NAME/STATE/etc columns:

    NAME                       STATE     READ WRITE CKSUM
    dummy                      ONLINE       0     0     0
      mirror-0                 ONLINE       0     0     0
        /tmp/dummy-long-1.bin  ONLINE       0     0     0
        /tmp/dummy-long-2.bin  ONLINE       0     0     0
      mirror-1                 ONLINE       0     0     0
        /tmp/dummy-long-3.bin  ONLINE       0     0     0
        /tmp/dummy-long-4.bin  ONLINE       0     0     0

However, if the zpool name is longer than the zvol names, alignment
issues arise:

    NAME                  STATE     READ WRITE CKSUM
    dummy-very-very-long-zpool-name  ONLINE       0     0     0
      mirror-0            ONLINE       0     0     0
        /tmp/dummy-1.bin  ONLINE       0     0     0
        /tmp/dummy-2.bin  ONLINE       0     0     0
      mirror-1            ONLINE       0     0     0
        /tmp/dummy-3.bin  ONLINE       0     0     0
        /tmp/dummy-4.bin  ONLINE       0     0     0

`zpool iostat` and `zpool import` are also affected:

                  capacity     operations     bandwidth
    pool        alloc   free   read  write   read  write
    ----------  -----  -----  -----  -----  -----  -----
    dummy        104K  1.97G      0      0    152  9.84K
    dummy-very-very-long-zpool-name   152K  1.97G      0      1    144  13.1K
    ----------  -----  -----  -----  -----  -----  -----

    dummy-very-very-long-zpool-name  ONLINE
      mirror-0            ONLINE
        /tmp/dummy-1.bin  ONLINE
        /tmp/dummy-2.bin  ONLINE
      mirror-1            ONLINE
        /tmp/dummy-3.bin  ONLINE
        /tmp/dummy-4.bin  ONLINE

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Gaydarov <git@gg7.io>
Closes #6786