LU-11299 lnet: net aliveness

LU-11299 lnet: net aliveness

If a router is discovered on any interface on the network, then
update the network last alive time and the NI's status to UP.
If a router isn't discovered on any interface on a network,
then change the status of all the interfaces on that network to down.

Test-Parameters: forbuildonly
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: I1d67eb4b3284ccb8306ad4c877a2fcbdf4958d8c
Reviewed-on: https://review.whamcloud.com/34510
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Tested-by: Jenkins