LU-10522 utils: new --mindepth for lfs find

LU-10522 utils: new --mindepth for lfs find

Added [--mindepth | -d] option for 'lfs find' to print
only the results found after N levels. Similar usage to existing
mindepth found in find.

Signed-off-by: Maximilian Dilger <mdilger@whamcloud.com>
Change-Id: I7816e27355f6796edc8437f700342da1b7e564d0
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55226
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>