LU-17431 nodemap: allow handling an id map for a dynamic nm

LU-17431 nodemap: allow handling an id map for a dynamic nm

Adding or deleting an id map for a dynamic nodemap, by sending the
appropriate ioctl to the MDS or OSS device.
On kernel side, we need to allow handling an idmap for a nodemap even
if the nodemap config file is not accessible (i.e. we are not on the
MGS). This dynamic nodemap is not stored on disk.

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I055cf1d67b72a6bca5140814c4346ac578f2f31d
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/54509
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: Marc Vef <mvef@whamcloud.com>