LU-16822 lnet: always initialize IPv6 at start up

LU-16822 lnet: always initialize IPv6 at start up

Currently lnet_inet_enumerate() has a bool parameter that enables
collecting IPv6 addresses for selection which is optional. This
patch changes the behavior to always collect proper IPv6 addresses
and now the bool flag means prefer the IPv6 over any IPv4 addresses.
Update the user land applications lctl and lnetctl to send a flag
to select IPv6 or IPv4 at initialization of the LNet stack. This
is useful for IPv6 and other large NID type testing.

Test-Parameters: trivial testlist=sanity-lnet
Change-Id: Ib3f38de15b1295ec1f8e8607dbd971583541f06c
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51818
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>