Adding the --file-layout (-f) option to zdb(8) to display the

raidz file layout for a given file. This leverages the internal
vdev_raidz_map_alloc() function to find the map of how the block
data is laid out across the child disks.

The column entry for each row looks like:
+------------+
|  D2     43 |
|     6020da |
+------------+
representing here the logical data column 2 that is 43 sectors high
starting at sector 0x6020da.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: sean.fagan@klarasystems.com
Signed-off-by: Don Brady <don.brady@klarasystems.com>

Author: Sean Fagan