LU-18114 nodemap: split "lctl nodemap_*" group into subcommands

LU-18114 nodemap: split "lctl nodemap_*" group into subcommands

Split "lctl nodemap_*" command group into subcommands, e.g.
"lctl nodemap_add" to "lctl nodemap add". And "lctl nodemap_*"
commands in sanity-sec.sh are modified to verify this patch.

Also, the old man pages are modified to reflect the new command
format, and the new man page references for lctl-nodemap_xxx.8 are
added to match the old ones.

Test-Parameters: testlist=sanity-sec

Signed-off-by: Emoly Liu <emoly@whamcloud.com>
Change-Id: I165583d95f4a850ce2461c15c56583d64077ef16
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56207
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Marc Vef <mvef@whamcloud.com>