LU-16622 utils: 'lfs find --ost' supports index range

LU-16622 utils: 'lfs find --ost' supports index range

'lfs find --ost' command can accept an index range. For example
    lfs find --ost 0,1-3
It equals to:
    lfs find --ost 0,1,2,3
'lfs find --mdt' can accept index range too.

Signed-off-by: Lei Feng <flei@whamcloud.com>
Test-Parameters: trivial
Change-Id: I094aa480c97440dad8ffaac8af902682b5916d6c
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55902
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>