LU-18469 ptlrpc: Add flag to deny mounts for nodemaps

LU-18469 ptlrpc: Add flag to deny mounts for nodemaps

Previously, nodemaps could only be activated and deactived globally.
This patch adds the ability to deny mount attempts for individual
nodemaps.  Existing mounted clients are not evicted when the new flag
is set.

This feature is implemented by adding a new nodemap flag "deny_mount"
and it is stored in the nodemap IAM config record. It is therefore
persistent and the flag is automatically distributed across the
cluster.

Similar to other nodemap flags, the new "deny_mount" flag is set via
"lctl nodemap_modify" and retrieved via "lctl get_param".

Deny mounts for nodemap:
lctl nodemap_modify --name <nm_name> --property deny_mount --value 1

Allow mounts for nodemap (default):
lctl nodemap_modify --name <nm_name> --property deny_mount --value 0

Read nodemap deny_mount flag:
lctl get_param nodemap.<nm>.deny_mount

A new sanity-sec test 74 was added to test this flag.

Signed-off-by: Marc Vef <mvef@whamcloud.com>
Change-Id: Ibf05d3e04768a5702dc6070e2d35c9ac07e731ac
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57096
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>