LU-7495 utils: add --links option for lfs find

LU-7495 utils: add --links option for lfs find

This adds a "--links" option for lfs find to filter files and
directories by the number of hard links. It also adds a printf format
'%n' to print the number of links for a file.

This commit also fixes '-l' as a short option for '--lazy' which was
added in 11aa7f8704c490b011f60f234c3ac9929ce76948 but the short option
did not work.

Signed-off-by: Thomas Bertschinger <bertschinger@lanl.gov>
Change-Id: I5d15bc290df8e8a08402f8d5cfa0a7139791b0a4
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50886
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Anjus George <georgea@ornl.gov>
Reviewed-by: Oleg Drokin <green@whamcloud.com>