LU-9680 obdclass: user netlink to collect devices information

LU-9680 obdclass: user netlink to collect devices information

Our utilities can report to users a device list with various bits
of data using the debugfs file 'devices'. This debugfs file is
only by default available to root which prevents regular users
from collecting information. Enable non-root users to collect
the same information for lctl dl using netlink. The advantage of
using netlink is that it also removes the 8K ioctl limit. Add the
ability to present this data in YAML format as well.

Change-Id: I5e6378765bd2f4c415cf29b2bc54adf0e54f308b
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/31618
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>