LU-17367 utils: improved hostname and IPv6 NID support

LU-17367 utils: improved hostname and IPv6 NID support

Improved NID parsing to accept hostnames, IPv4 and IPv6 addresses.
IPv6 addresses need @network to be parsed properly. The following
is a valid IPv6 address: "6699:7654::1234:1234:d84@tcp"

All other non IPv6 addresses can be passed in without a network
identifier.

Signed-off-by: Maximilian Dilger <mdilger@whamcloud.com>
Change-Id: I131c8b2d1f7b0fe593564af90308d2d3ea278a0c
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55706
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mikhail Pershin <mpershin@whamcloud.com>