LU-18076 lfs: get client UUID by "lfs getname -u"

LU-18076 lfs: get client UUID by "lfs getname -u"

This patch is to get client UUID from the mountpoint by command
"lfs getname -u" directly. Functions llapi_file_get_type_uuid()
and llapi_file_fget_type_uuid() are added, and the man page
lfs-getname.1 is updated as well.
Also, function get_client_uuid() in test-framework.sh is modified
to verify this patch.

Signed-off-by: Emoly Liu <emoly@whamcloud.com>
Change-Id: I8f7db964adf209e19c29a240608881b38e068ded
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56437
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Zhenyu Xu <bobijam@hotmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>