LU-7845 obd: add 'network' client mount option

LU-7845 obd: add 'network' client mount option

Add a 'network' mount option on client side. All connections made by
the client must be on the LNet network specified in the 'network'
option.

This option can be useful in case of several Lustre client mount
points on the same node, with each mount point using a different
network. It is also interesting when running Lustre clients from
containers, by restricting each container to a specific network.

This new option is added by tampering with two config commands:
- setup: add a fourth parameter, which is the net to restrict
  connections to. This parameter will be passed down to
  ptlrpc_uuid_to_peer() so that client only connects to peers on the
  restricted network.
- add_conn: skip this command if uuid to connect to is not on
  restricted network.

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: Ica7ab6ebe7c2c9e7b0409b615e90d9271c31e92f
Reviewed-on: https://review.whamcloud.com/19792
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>